No feedback on cancellation & offering a contract but fail to deliver

I've spoken to 3 different consultant regarding a cancellation that im still being billed for it's been 4 months now. I'm sent a cancellation form, I didn't receive feedback so I called after a month only to find out I didn't complete the serial number of the device. A consultant then "assisted" me by completing the form. I'm still being billed for this contract that expired!!

On top of that I received calls that my contract expired and I'm due for an upgrade. I said to these consultants numerous times I'm not interested because they haven't cancelled my old contact yet, because I'm still being billed.

About 2 weeks ago I received another call again for the upgrade. I then asked the consultant if I take a upgrade would it automatically cancel my old one that I'm being billed for and he said yes. I was proceeded with the process to get the upgrade. I was told that this new phone will be delivered within 5 working day.

Last week I received another call and they wanted to offer me the upgrade again, so I said to the consultant but you guys called me and I agreed and was promised the upgrade will be delivered in 5 days. The guy apolozed and said his system might not be updated and he hung up.

I'm now still being billed and I'm sure i can't expect a upgrade soon. I give up!!!