Sort this problem out. N give me the service that is needed

I have been having problems with Mondo and MTN with regards to ******** debit orders which have been deducted from my bank account. I cancelled my services with them within 7days of taking up a data contract, as they had problems activating the SIM. This cancellation should have been done in January on 2021. They started their deduction from march and at the point of me noticing this I had called them to enquire.. each month they kept on increasing the amount as the cancellation was not processed until the 19th May 2021.i have not received my refund to-date and have been calling time n time again to get this resolved. Every agent I have dealt with has assured me they will get this resolved. The manager /team leader had mad contact with me and assured me this has been escalates n I will get my refund.. I am still waiting. What does one need to to to get their money back.. if I don't get resolution on this with the day I will start by complaint again and will do a name and shame for every one who has confirm d they will sort this out. Mondo & MTN. The ball is in ur court. I am still being calm.