Bad Experience by MTN

I would like to just get this out here, since I'm being ****** in daylight! In April I received a phoendcall from MTN offering me a package deal with a Huawei Nova with a smart watch, however it took them a month to deliver the package. When the package eventually arrived it came without the smart watch which was agreed upon. I then immediately took it back to one of the MTN branches in Port Elizabeth Greenacres consultant assisted me very nicely and convinced me that within 30 days the contract will be terminated. After alot of calls messages emails I was gald that it's finally over. Then I receive an invoice from them billing en for who knows what and immediately I phoned in. After months of trying to get hold of someone who could assist me I received another bill. I am highly upset I am now being billed every month for a phone I returned within the 7day period unopened..I am about to take legal action against MTN cause every branch this far keeps telling me that there's nothing they can do. If here's anyone out there that experience this please contact me I don't know what els to do I would never recommend MTN ever again they are a disgusting Company I'm so sorry for the next person they will do this to. My whole credit score is affected by this.