Cancel my contract

I app**** for a contract phone online Samsung Galaxy S21 which I received but when I activated the phone there was no data no airtime as agreed and besides that I didn't like the phone so I went to a MTN store near me and returned the phone 2 days after hoping I would love it but not so the took the phone in store as it was still in a period that I can return it that was in February 2021 but till date I'm still being debited for a phone I don't even own I've been calling MTN and they say they will cancel my contract I even asked if is there anyone handling this account and they said no.