MBD Bad service!!!!!!

I was notified by MBD that my Mr price account was handed over to them. I then fully paid my account balance including arrears I had with MBD. I sent them all my payment of proof attachments on emails and called them several times for my Paid up Letter. They never sent it and it’s been 3 months now and no further information has been given to me. Everytime I call a manager would say they will call me back but no luck. I am really disgusted at this company. They do not solve any queries but all they want is money. I paid up but no Paid up letter. Suing them would be the best issue right now. Making complaints with them but still no resolution. Bad bad bad service. Angry client