Cellphone upgrade

I have been with CellC for almost 10years now and never have i been treated like I'm not of value as a customer in the past few weeks. I went under debt review some time last year but decided to cancel after a few month as i saw it was better to pay my own debt. I was due for an upgrade from Feb 2015 and i went to the branch to upgrade. They required the cancellation letter and i produced it but still no feedback. I then called the call centre and they said i should e-mail the letter. I did so and they keep on sending me from pillar to post when i call to find out if they have received it, i am so irate and wants to close my contract Cellc as soon as the contract ends. When i call Customer care they send me to legal...Legal then sends me to another department. I am so tired I just need someone to do their JOB!!!