WORST SERVICE

I am so angry with MTN and will never in my life do business with them again. I opened a contract with MTN two years ago and paid the account well through a debit order. I paid up the account in 2019 MAY. Today I received a message that I owe them R1679. I paid up my account and I have proof that I requested them to cancel my contract. I even wrote on their Facebook page. Today after a year, boom they say I owe them. I hate MTN and will never advice anybody to open an account with them. They say my reference is ***.My name is Modiba MM, My ID no is ***