Bad client experience from MTN

Recently I have had a bad encounter with MTN. I cancelled my contract with ing the cooling off period and now I’m told I’m owing because it was billed. And no one is calling me for updates on the query no one is assisting all of them are telling me I must pay. How bad is that. They all promised me that the team leaders will call but they never do. Their agents are rude the other one by name Xoliswa was even talking over me on the phone and telling me they way I’m so disrespectful yet I’m the one who needs help. I wouldn’t call if I didn’t need help. At this point I want to cancel my other 5 contracts with them and move to another provider because it’s clear they don’t appreciate us as clients.