Charges for an Apple Watch I returned

I went to the ATT store June 5th. Both my husband and I upgraded our phones and took advantage of the BOGO watch sale. I was also talked into a 3rd watch for signing up with firstnet. I told the rep I didn’t need it, but he insisted I take it because it was free. Later that night, I decided it was a silly idea and called customer service to return it (unopened, in the box). The woman I spoke to said I could return it free of charge and as long as I sent it back within 30 days, I wouldn’t not be charged. I was sent a return label and I shipped it the next day. I waited until I received email confirmation stating it was received before calling att back to cancel the line (as instructed from the first rep). Now I have a $320+ charge on my bill for the watch! I called customer service back and they said they have no records of who I spoke with, what was said, or any information regarding the watch. I, unfortunately, deleted the email with the tracking and the confirmation thinking that I was in the clear (obviously this was a wrong move). The rep told me the best she could do was create a report to send to corporate and see if they can resolve this. Has anyone else felt with this? What was the outcome? I wish I didn’t delete the emails, but also I’m very disappointed with ATT that they have no records on their end. Isn’t their calls “recorded”?! How do they not have record on their end?!