MTN is billing my account illegelly

I had a contract with MTN that expired on the 9th May 2015. I informed them well in advance that I did not want to renew my contract. they Informed me that my account would not be debited when my contract expired. To my surprise, they've been debiting my account even after the contract had expired. If you try to call them their call centre is not working. you hold for hours without getting any assistance. I'm very annoyed and I think I should hand the issue over to my lawyers.<br> <br> I would advise everyone not to take contract from MTN!!!!