Refusal to take back their phone and billing me

I got a call from Cell C to sell me a contract phone I was interested in LG G4, they delivered LG but the wrong model and wrong pricing as agreed with their call centre agent. <br> <br> I then called them to come and take back their phone and I am cancelling the contract, they gave me the ref number for collection when I make follow up for them to collect the phone I will hold for more than 30 minutes I will then explain my story then the call centre agent will drop the phone and it happened more than 4 times. I am not using the phone and their billing me his is not fair from Cell C.<br>