MTN contract sim swap

On the 29th of August 2019 my cellphone was ****** and on the 30th of August I went to MTN for a sim swap but it failed because they say the verification sms is sent on the same number I have lost. Everyday I spend about two to five hours and they have tried 6 attempts to change the number but still they failed, today is 7th of September my number is not back and it's a contract sim card that I am paying for every month. Since it seems they can't help me out, I am seeking advices if I should cancel my contract with them or what to do, I called the call center almost every day even twice but they say they cannot help me still. I am stuck and my business number