Billing-Cancellation-Customer Service Issues

Hello,  we seem to have an issue with our account.  We had presumably attempted to disconnect our service quite some time ago.  We were continued to be billed and debited from our Bank Account.  Called in last month to discuss issue.  Was then credited back monies from last 5 months.  All seemed good until we got a bill for those same months again?  We have not had (or should not have had service) since Jan 2023 I believe.  Our mistake is that I don't have any confirmation number, representative ID, or exact dates of call to disconnect and port only one of our #'s.  The other remaining should have been taken out of service.  We never received paper bills for Feb-June 2023.  Our bookkeeper did not notice until I noticed, hence the call on June 28th or 29th.  We did receive a paper bill dated July 6th stating that we now owe monies that were credited back to us?

The last representatives on the phone were less than professional and quite rude during conversations.  The last representative said he would not be able to talk about this or assist.  He told me the ONLY way to get help is through the forums?  Customer Service is the real reason we decided to switch providers last year, this situation only vets that decision.  

We were charged for services that were supposed to be cancelled.  ATT rep realized mistake, credited account, assured that the account is cancelled.  Move forward a few weeks, someone noticed multiple issues now we owe monies???  Rep told me that there is nothing we can do, even though he admitted to mistakes on ATT's part.  No conversation facilitated, just a statement and then told me try on Forums???  Would not escalate issue or allow me to talk to another supervisor???

Does anyone know someone other than a REP to talk to?  How can a customer escalate an issue to another department that actually listens to customers and not talk over them repeatedly, get defensive or raise voice to customers?  Does ATT even screen these support calls?  

HELP!