customer complaint - terrible service

I had attended to an upgrade and get my monthly statement of account to see I am now being charged for an additional line. I have been in contact with them a number of times by call email ect and still noting has been done. I did not take out a new contract and do not have a new device and just need this to be cancelled at no cost to myself as it is not something I have signed up for and they just keep pushing me from one department to the next and not getting anywhere. I am now hoping that this will work