I took a warrenty item into store as they are 15 minutes from work. I’ve found part of their “charm” is that you get a different answer depending on who you speak to on the phone. The guys in the store have always been helpful in my experience.
Suggest phoning the store in question and confirm that you will be returning it in person. I think I completed a returns form and dropped it off with my warrenty item no problem.
Edit: sorry just seen you tried to call. If the shop is local then I’d suggest just dropping in. A quieter time of day will probably help.