Do Not Subscribe to Supersonic!!!!

Supersonic is the most useless service provider that exists. Please DO NOT sign up with them. I moved houses and transferred my line and they neglected to cancel the line for the previous address and have been double billing me. I have been trying to obtain the correct bill for the last 3 months not and they fail to resolve my query. I have since cancelled by service and they are now refusing to release the line. Pathethic, useless call center agents and managers and supervisors who are never available. Please can someone assist urgently!!!!!!!!