MTN Contract

I had a 24 contract with MTN which was supposed to end in June 2015. MTN sent me an sms in April notifying me about the upgrade, I called them and I told them that I want to cancell my contract. The consultant told me that I need to call in June. I called in June I spoke with the other lady who told me I must call after they had debited my acount. I called after they debited my account no one picked the call. I tried and tried no one one pick up the call until the other lady picked it on saturday and told me that they will run a debit order on my account because I was suppose to call in June, I told her I did and no one picked the call and she told me that MTN was on strike. It is not my problem that MTN was on strike and no one picked the call. I want MTN to cancell my contract, I dont want their airtime and bundles for this month and I dont want them to debit my account. My contract with them was for 24 months not 25 months.