Trinity Kays Kulture

I purchased a pair of pants from Walmart.com Marketplace vendor Trinity Kays Kulture in my usual sizeThe pants did not fitI inquired about an exchange and was told exchanges are not possibleI was told to return the pants at my own shipping expense and order a new pair
I left feedback to Walmart.com that I didn't realize I was buying from a Marketplace seller and would be unable to return the pants to the storeA Walmart customer service rep unexpectedly, but kindly replied and contacted*** *** at Trinity Kays Kulture on my behalf asking if he could provide a prepaid shipping labelHe said no, but agreed to reimburse the cost of the return shipping if I emailed him a copy of the shipping receipt, which I did
*** replied to the email with the shipping receipt to tell me that the return shipping "cost a lot" and asked why I used FedEx instead of USPS first class mailI was never advised by*** or the Walmart rep on how to ship itI don't know a lot about shipping