Account handed over to SSDA

I am very frustrated, <br> <br> I have been receiving phone calls and smses' demanding I pay R9500.00 something from SSDA. they claim that mtn had handed over my account to them because of not paying.<br> <br> There's a few things I do not understand and Im hoping mtn can contact me since I have posted here.<br> <br> 1. Every time I go to the branch to enquire about this they tell me they do not have my details or the account does not exist,<br> 2. The phone I had on contract was R100something pm - mtn was debiting every month until the contract length ended (24months).<br> 3. I had this account in 2***, why am I only being contacted the passed couple of months about this?<br> 4. my credit records for 2012, 2013, 2014 & 2015 shows that I have paid up my MTN account and that I am not owing anything.<br> 5. Mtn asked me to upgrade and I refused and said I will be cancelling the account- how come this matter was not completed?<br> 6. when I told mtn I will be cancelling the account they said the sim card will no longer work and I said its fine and from there on I used another service provider.<br> <br> with all of this said and done- WHY DO I NEED TO PAY R9500.00??<br> <br> I cannot understand this