Cancelation

My name is charles I've got my account with vox for about a year. During this time my 20 meg line has never run at at least 17megs. Always at 7-9meg. I phone vox on a weekly basis but no joy. I'm trying to cancel my contract but due to no internet i'm forced to phone and cancel. Everytime i phone i have to hold for at least 20min. **** when i explained it to the technical deparment; we will put you through. No can we keep our customer. Please cancel my contract now!!! Charles