Landline Account Issues

Among my various AT&T accounts, I have a land line account that I keep in service in case of emergency.  I have never been able to add the account to the MY ATT app and for the last 6 months when I attempted to pay my monthly statement, either by phone or online, my account is not recognized and I must speak to a representative to make the payment.  Each time the representative tells me that the issue has been resolved and that I will be able to make the payment by phone or online the next month, but each month the problem still occurs.  Yesterday, when I again attempted to make payment via the phone, and my account was not recognized, the representative attempted to charge me an additional $5 for representative assistance  in making the payment.  When I objected, the representative waived the fee.

Due to the issues that I have this account, I informed the representative that I wanted to cancel the account and representative stated that he would forward me to the appropriate department.  When a new representative got online, he asked for my account number, which I read off my statement.  The representative then proceeded to inform me that the account did not exist.  When I asked to speak to a supervisor, the representative told me that I could not speak to a supervisor without an account number.  When I read to the representative the account number one more time, he again told me that the account number did not exist and refused to forward me to a supervisor.  When I persisted, the representative stated that he would forward me to a supervisor, but then I was placed on hold and no one picked up the phone.

I am at my wits end.  I don't want this account anymore because AT&T has made it impossible to pay, but I am not able to cancel this account.  Is there any representative of AT&T that will assist me.