upgrade cancelled but still billed

I had requested an upgrade but after an offer from another cellular provider, cancelled the mtn upgrade, but only on the day of delivery called the corporate call center and was told an administrator would contact me for someone to pick up the device and I would not be charged!! , this went on for about a week with numerous calls for the phone to be picked up, eventually I was contacted and the device was picked up still<br> sealed, today I receive a d/o that clearly shows I have been billed for a cancelled upgrade.