How do I complain to Virgin media and actual get them honour what they promise.

Hi all, new poster here but Virgin user for many many years

Usual tail of woe here, contract renewal in January, following expiry of my existing contract, I get what I think is a good deal rather than pay £166 bill. Come February I get billed the full whack not the negotiated price despite a contract, I complain, get fobbed off with  "yes you are right it will get sorted", come March the same happens, come April the same and come May, guess what ? the same (but with a refund), log onto my account and it still says "deal expired" despite having 3 agreed contracts to the contrary, texts, transcripts, recordings, etc but to no avail, all operators say "I'm really sorry and I will sort it out" but they never do. So the long and short is that I am being overcharged contrary to an agreed contract, they haven't honoured any of the contract items to what was promised. End result is breach of contract and overcharging (illegal?). This service is appalling and I feel really aggrieved having wasted my valuable time trying to sort out what is a fairly simple thing. I hate to say it but I'm really considering moving provider I've even lodged an official complaint but it doesn't seem to make any difference what so ever.

My question is, does anyone here have any advice how to escalate this to someone who really cares and can get things done or is that to much to ask.