2nd Credit Bureu instructed on paid up and cancelled contract

MrP Mobile have now instructed a second credit bureau to collect money from me. The first one got copies of approx 35 mails between myself and MrP Mobile - one of which was from them confirming my account is up to date. I continued paying the money every month, despite the fact that the phone was ******. I paid right till the end of the contract term and gave the required written 30 days notice of ternination. I have every EFT I did as proof. I sent the credit bureau everything I had. I never heard from them again. Now 7 months later some other credit bureau is trying to get money from me. Nevertheless, even after cancellation they continued to present debit orders for different amounts. I had to reverse them all. Now they claim they are unpaid due to insufficient funds. No matter how many times I say reversal, they just don't hear. Their accounts department needs revamping and to be headed by someone who can actually count and reconcile accounts. I have advised this bureau that if they continue to contact me I will consider this threatening and harassment. My advice to everyone is avoid MrP Mobile like you would Covid!!!