Mtn refuse to cancel a contract of mine regarding the number ***

I called in December to inform that my contract is expiring on the 20 January 2022 informing the customer agent that I would like to discontinue the contract as that is my last month for the numbers *** now I'm told I cannot cancel the contract with out giving 30 days notice but the contract was a 3 year contract and the term had came to an end as per agreement the agents promised to call me back to assist until now no call back .I called back and when asked to speak with a supervisor they drop the call can I get any assistance