Can't get ANYONE to cancel my contract

I called retentions two weeks ago to cancel my contract. I was given the cancellation amount that would have to be paid. I paid the full amount immediately after the call and emailed the proof of payment. I was told that my contract would be cancelled within 48 hours... its now been 2 weeks and it is still not cancelled! I called retentions again and they put me through to customer service who then put me through to someone else and the call was cut. I tried calling retentions again and my call keeps getting cut. All I wan't is to cancel my contract and go onto prepaid so that I can port my number.