I cancelled this contract. Why are you billing me?

My contract lapsed in 2020 and was on a month to month. Last month I cancelled it and you guys are still sending me collection sms's. I do not need the contract hence I have cancelled it.

I called in again this morning 3 times and keep getting cut off. I spoke to one consultant who eventually just went quiet and didn't even call. My number is ***. Please make sure this is cancelled