Mtn debt collectors again.

Getting highly annoyed with MTN.

Debt collector emails saying I owe R15878 and when I email mtn because MTN does not respond to complaints telling me they will tell me where they pull this amount from the legal department replies saying I owe over R4000. This is really working on my nerves I don't pay unless I know what it is. And the last complaint I got a response they will let me know and no one got back to me. I want a break down of this R15000 amount.