Arrears for a paid up account

I think I had it with Cellc . I had a contract with them for over 10years did several upgrades and decide that I am done with he contract and contract ended.

Since 2021 I have been receiving calls stating that I am in arrears with the account , which never happened debit order went off as per usual each month without fail . VVm called to say I am I arrears I forwarded documents to advise I have been paying they stopped calling me and advised that my account is fine a few months back I am getting calls from Nudebt stating I am arrears . The **** part of all this is I am in arrears but I am on a pay as you transact account which is prepaid . My line has never been suspended or phones has been blocked but I owe them . Loyal customers are being ****** B-road day light .

When I call the collections team they do not have answers neither does ***** or anybody in cellc have an answer how am I owing the account all you have to do is speak to the debtors that has no clue themselves what’s happening all they asking is for a pod up letter .

I am sick of this network please help