Disappointed

I had a contract with MTN that I settled long time ago beginning of 2024 in February they even charged me cancellation fee and I payed it later on they said I payed more I must be refunded I sent all the required documents and they never paid me hey changed statement and said there is no money that is due to me Today I received an email saying I owe MTN R574.00 and I do not have contract with them I settled everything with them