I was always under the impression that you cannot return multiple items in one box if they were not sent to you in a single order.
You sent back three items in one box. one was defective and should not incur a shipping charge. The other two would incur shipping charges because they were not defective.
So, if you were charged for returning two items, you would incur two charges.
If you purchase something and use PayPal, they will refund your return shipping charges up to $30 for each return, up to 12 returns a year. You have to sign up for that perk before you use it on their website.
Looks to me that you tried to save money on returns by packing three items together and it backfired. I don't know what items you returned, but it probably cost QVC more than $6.95 shipping for that box to be returned. How do they figure out how much the free shipping item cost and subtract that from the total they paid for total shipping?
You could have returned all three items sent back separately and and had all of your shipping charges returned to you by PayPal. It would have cost you nothing.