MTN won't cancel my contract!

I called 135 to cancel my MTN contract. I got a ref no for the cancellation but my phone number is still on a contract two months later???

Ref number: ***

I have tried to call the 135 number numerous times to find out why I am still on a contract but the MTN customer service center is extremely poor and I cannot get hold of anyone even after waiting 1 hour on the line.

Please cancel my contract and ensure my number remains on prepaid for me to continue to use MTN.