QVC's operating expenses are principally comprised of commissions, order processing and customer service expenses, credit card processing fees and telecommunications expenses. Operating expenses were 8.4% and 7.8% of net revenue for the three and nine months ended September 30, 2022, respectively, and were 7.3% and 7.1% for the three and nine months ended September 30, 2021, respectively. Operating expenses increased $3 million and decreased $22 million for the three and nine months ended September 30, 2022, as compared to the same periods in the prior year. The three month increase is primarily due to a $6 million increase in telecommunications expenses, and a $3 million increase in personnel costs driven by higher wages at QxH. The increase in costs was partially offset by $10 million as a result of favorable exchange rates. The nine month decrease is primarily due to a $22 million decrease as a result of favorable exchange rates.
QVC's SG&A expenses (excluding stock-based compensation) include personnel, information technology, provision for doubtful accounts, production costs, and marketing and advertising expenses. Such expenses increased $28 million and increased $39 million for the three and nine months ended September 30, 2022, respectively, as compared to the same periods in the prior year, and as a percentage of net revenue, increased from 10.8% to 13.5% and from 10.5% to 12.6% for the three and nine months ended September 30, 2022, respectively, as compared to the three and nine months ended September 30, 2021. For the three months ended September 30, 2022, there was a $14 million increase in personnel costs across both segments, a $14 million increase in marketing primarily at QxH and to a lesser extent QVC International, a $5 million increase in consulting expenses at QxH, and a $4 million increase in rent expense, primarily at QxH. These increases were partially offset by a $17 million decrease due to favorable exchange rates. The increase in personnel costs for the three months ended September 30, 2022 was due to higher wages across both segments. For the nine months ended September 30, 2022, the increase was primarily due to a $28 million increase in credit losses, primarily at QxH, a $14 million increase in marketing expenses primarily at QxH and to a lesser extent QVC International, a $13 million increase in consulting expenses primarily at QxH, and increases in IT expenses, non-income related taxes and rent expenses. These increases were partially offset by a $35 million decrease due to favorable exchange rates. The increase to estimated credit losses for the nine months ended September 30, 2022 was due to lower expected collections in the current year compared to favorable adjustments recognized in the prior year based on actual collections experience.
For the three months ended September 30, 2022, the gain in the fire related costs, net of (recoveries) line primarily related to insurance proceeds received for inventory and fixed asset losses. For the nine months ended September 30, 2022, the gain primarily related to insurance proceeds received for inventory and fixed asset losses partially offset by write-downs on Rocky Mount inventory. Fire related costs, net of (recoveries) includes expenses directly related to the Rocky Mount fulfillment center fire net of expected and received insurance recoveries. Expenses indirectly related to the Rocky Mount fulfillment center fire, including operational inefficiencies, are primarily included in Cost of goods sold. These indirect expenses will be submitted as part of QVC’s business interruption insurance claim; however, there can be no guarantee they will be recovered.
QVC recorded $277 million and $520 million of gains on sales of fixed assets for the three and nine months ended September 30, 2022, respectively. For the three months ended September 30, 2022, the gain related to the sale leaseback of five owned and operated U.S. properties. For the nine months ended September 30, 2022, the gain was primarily related to the sale leaseback of five U.S. properties and the Ontario, California distribution center.
QVC recorded impairment losses of $2,715 million for the three and nine months ended September 30, 2022, related to the decrease in the fair value of the HSN indefinite-lived tradename and the QxH reporting unit as a result of the quantitative assessments that were performed by the Company (see note 5 to the accompanying consolidated financial statements).
Stock-based compensation includes compensation related to options and restricted stock units granted to certain officers and employees. QVC recorded $9 million and $27 million of stock-based compensation expense for the three and nine months ended September 30, 2022, respectively, and $13 million and $33 million for the three and nine months ended September 30, 2021, respectively. The decrease in stock-compensation expense is primarily due to the retirement of QVC’s former Chief Executive Officer.
Depreciation and amortization decreased $17 million and $10 million for the three and nine months ended September 30, 2022, respectively, and included $15 million of acquisition related amortization for both of the three months ended September 30, 2022 and 2021, respectively, and $46 million for both of the nine months ended September 30, 2022 and 2021. The decrease for the three and nine months ended September 30, 2022 was primarily related to a decrease in