MTN Upgrade issues

I recently upgraded my contract to a different contract type over the phone and i was told it will soon be processed. To my surprise when MTN debited from my account they an amount that is more than what is expected. I called and i was advised that my previous contract had expired and that im going on a month-to-month basis hence the high amount. I told them that i have upgraded and they are able to see it but to date my account is still running on a month to month basis and i cant even cancel my contract because they say i have 2 pending contracts which need to be approved and i cannot cancel my contract. This is annoying as MTN will be debiting an amount that is high than what i expected even though ive upgraded to a different package and cant even cancel my contract, no one from MTN seems to be able to assist with this issue even when i go to the MTN outlets they keep referring me to call MTN instead