Frustrating closure and ******* handover

It's rather getting sour now. I'm really frustrated with Discovery bank. I've requested closure of my bank account. everything was ok. because it's linked with Vitality along with a watch, i cancelled that also. they call me after a couple of days indicating that I need to pay for the watch. I'm like ok I don't mind doing that, I'll give you my updated details and then you can deduct as you usually do. they said they'll call me and see what the way forward is as i was not told by the consultant who has a call with our company when leaving discovery medical aid what will happen to attachments. Ever since I've been waiting for that call.

Now today i get a call for some collections company saying my details have been handed over. i refused to continue with the call and explicitly explained to the caller that i will not action anything or event entertain your call because 1. They have not sent me any communication and 2. I don't know you. he continues to say i must do my due diligence? like how if the procedure or process was not followed?

the only comms in this process was the account settlement which I'm still struggling to do. i don't know why it has to be so difficult to just close and now again I've experienced further charges on the card increasing my outstanding. This is getting ridiculous. if I'm wrong, i plead with discovery to show me proof of the comms the collectors where talking about

It's really disappointing