Supersonic refuse to release my line.

Cancelled my account on 2 Dec. Was promised that line would be released at end of the month. 18 calls later averaging 35 /55 Min. still no response.Super useless and ***********. Been promised 8 times that a supervisor would contact me. They refuse to release my line . February now and still struggling. DONT WASTE YOUR TIME WITH THESE INCOMPETANT ******.