Angry mitchells plain resident

Very dissappointed with my service from supersonic have my fibre with them suppose to be a 20mbps line bt im runing even less the a adsl line 0.34mbps and yesterday i had no internet for the whole day all they can say is theres a issue in area whdn i asked how long no response fron them up until now im getting no response from them im paying for something i have no use of and would like to cancel and go with another isp as supersonic is really useless to there clients very bad customer service