Pathetic service from MTN and Rewards Co

i took a mtn contract with their third party consultants Rewards Co,the phone was delivered to me on the 13/07/2020,i had to send the device back as it was faulty,to date i have still being debited for this device which i dont have,i have contacted both mtn and rewards co numerous times with no joy,they pass the buck to each other and refuse to give me a definite answer on what is going on,i was advised that i should cancel this contract which i agreed to,now been informed it will take 4 weeks for the cancellation to be done and in the meantime i am stil being debited.This is terrible service and also a waste of my time and phone calls as no one i speak to tells me whats going on,i am extremely frustrated and will get legal advice on how to proceed further!!!!!!