Complaints against cellc

I would just like to share my experience with cellc. They are by far the worst service provider. I have recently paid up my cellc contract and requested a paid up letter. I have been calling for the past two weeks, all they do is put me through different departments. When I called on the 9th they said the paid up letter will be emailed within 48 hours so I called on Friday 12th and still have not recieved anything. I am beyond disappointed with cellc and will not support them in the future.