ATT was unable to connect DSL line yet I have a large bill with early termination fees.

My DSL service was not able to be connected by three technicians so the account was cancelled. I now have a $500+ bill that includes early termination fees. I called and was told that I needed to wait for the ‘revised final bill,’ then call back to have this all corrected. The support person told me I should take my modem to any fedex store and they would be able to return it to ATT at no charge to me with just my ATT account number. I explained that due to COVID-19, going to the store was not possible. She told me she would note that on my account. I asked for a return shipping label to be emailed to me directly so I could ship it via a drop box instead. I still have not received the label and would like this bill to be cleared. I have been on telephone support for a combined six solid hours and do not have time to wait another hour for no positive result. Where can I get a return shipping label?