Equipment Return - UPS or in store?

I just got into an argument with a very unpleasant store rep (M. Halston, 416 S. University Avenue, Little Rock, AR) who tried to refuse to take my modem return because he said it should be returned at the UPS store across town.  Ok.  The rep at the exact same store the afternoon before specifically told me to bring the modem back the store for a return.  I even asked about the UPS return when I picked up my replacement modem, and she told me NOT to do that.  I was annoyed then because I could have brought the faulty modem with me then to return, instead of having to make another trip in the next morning.  When I refused to drive across town to do the opposite of what I was told to do the day before, he reluctantly took it but refused to provide a receipt.  Literally said that I was wanting him to "do the work for y'all" when he was making excuses why he couldn't provide a single stitch of evidence the modem was returned.  Of course I want you to do the work for me.  I'm the customer.  Amazing.  I asked if I could take a dated picture of him holding it because I clearly can't trust that anything will be taken care of without proof, and he became extremely rude and belligerent.  Went on some rant about him being a father or something, I don't know.  Finally another rep came over with a receipt book, because people were starting to stare at that point, and the angry rep quietly filled out a paper receipt by hand and gave it to me.  Why was I told two different things from the same store about where to return the modem?  Why was writing out a paper receipt something to fight and embarrass a customer (and yourself) over?  I pay a premium for a service, but I'm the one running all over town to replace Xfinity's faulty equipment.  "This man-made equipment, made in Philadelphia," was the excuse given about the bad modem when the rude rep was trying to belittle me for making him do work.  Hire better people.  In your Little Rock store on University Avenue, and apparently in your equipment factory in Philadelphia.  They're catching blame from 1000 miles away.  At least he was aware enough not to try to sell me wireless service, or specifically ask me for a 10 on the survey like the rep the day before.  What a joke.