What isn't wrong with them?!

Upgraded phone when iPhone6 launched. Was promised phone within few days, turned into 2 months for a phone to be delivered. <br> <br> WRONG sim sent, had to purchase new sim to get phone activated<br> <br> Since upgrading, every month their billing is done incorrectly - double billing, sometimes triple<br> <br> Excessive data usage that cannot be explained. Cellphone account was previously R1700 av. but now R6500, R3500? And nothing wrong from their side.<br> <br> Nobody can tell me further than it was data usage - I work and live in WIFI so explain how it's possible. Account now in arrears as I've questioned this and made arrangements to pay just the contract amount this this is rectified yet they bill my account three times for the contract amount and the outstanding amount and more?<br> <br> WANT TO CANCEL THIS ACCOUNT IMMEDIATELY. Take the phone back, I don't care. Over poor service.