Termination of contract

I went to the Chatsworth MTN branch in April 2015, and they informed me that my contract with be up on the 23rd May 2015. They informed me that I cannot give a one month written notice, I have to phone 808 from my cellphone on the 23rd May 2015 and inform the call centre of the termination of my contract ***). I phoned the call centre on numerous occasions and no one was at the call centre and all the MTN store are closed. I have also emailed mtn customer service but no reply as yet. Mtn have already taken out the money from my account. It is getting very frustrating dealing with Mtn. Please can someone advise me on how I can sort out this matter.