MTN - Most Terrible Network

Had a contract with MTN back in 2014/2015. When the contract was about to end, I gave the amount of notice needed to cancel the contract. 8 years later, they are billing me R500 and have handed me over restricting me from taking out another contract.

Try to call any number provided for MTN and NOT ONE ANSWER FROM ANYONE! Not even their stores! Apparently I am not the first customer this has happened to.