MTN horrible service

MTN I've received horrible service I went to cancel the contract on the 4th Jan 21, at MTN store was quoted that I should pay R2550 I did that on the 13th went to store to cancel we waited long on call for retention department to attend our call the consultant by the name of Thabang was very rude and was telling me that I should pay more because I cancel the contract as if it's my fault that i quoted my self and I'm charged more than I owe