MTN unable to get contract terminated

I have visited the MTN store numerous times and requested that my contract must be terminated. No mentioning of 30 days notice. On the 5th June I visited the store again. Was requested to write a letter for cancellation and I did wrote the letter and was given in at the store. Reference number received ***. I was informed contract will end on 18 June 2015. Last payment will be end June. After phoning 808, all of a sudden there is a 30 day notice and last payment end August. This is not acceptable as you are *****ing R500 +- as I have done my part l. Followed instructions given by your people. Rectify this issue or I will get legal advice as contract expired on the 18 June 2015. The MTN stores excuse is that due to a strike all cancellations could not be done this after visiting them again today. They also do not know of the 30 day notice of cancellation. Their view is that the contract termination date was the 18th June. I am not going to pay for incompetence