MTN holds SIM only contract user ransom with ridiculous cancellation fee!

On a SIM only contract, MTN requires me to pay R2400 to cancel my contract and move to prepaid so that I port to a better-priced service provider. They provide a fourth of the value for the same price as their competitors. On a MyChoice +M they charge effectively the same as Telkom does on a FreeMe 20Gig. There is no effort on their part to try and retain me as a client. Their retentions department refuse even to move me to MyChoice +L. Total "no care" attitude.