It's sadly very common to read that customers find they are billed for different amounts to those offered and agreed as a result of a contract change. However, your legal rights are crystal clear - information provided by a company verbally or written is binding if the consumer relies upon it when entering a contract (Section 50, Consumer Rights Act 2015), not to mention established contract law that means a binding contract exists when an offer has been made and the offer has been accepted. So VM have to honour whatever was originally agreed.
Hopefully the forum staff can pick this up and get it sorted - by which I mean that you get exactly the deal you were promised, not some less attractive compromise, all over-payments refunded, and payment of compensation for the serious inconvenience and multiple failed chances to resolve the matter. That would be the cheapest and quickest resolution for both parties, and the best way of trying to recover some goodwill in a bad situation. If they can't get it sorted in that complete manner, you need to search, read and follow the Virgin Media Complaints Code of Practice, raising the complaint by recorded post (the online and phone options are unreliable). If you do need to raise a formal complaint reject the contract they're trying to impose, and demand that as per your legal rights the company honour what was promised, and pointing out that if the company can't honour its agreement you will escalate to the industry arbitration scheme CISAS as soon as permitted by the rules. In the meanwhile, don't do anything daft like stopping your direct debit, that'll be recorded as a credit default, and opens up whole new realms of difficulty for you.
If VM still won't honour the contract despite the complaint, then you've got two options to take the matter forward. The first is if you get a resolution letter from VM, you can reply, rejecting that and asking for a deadlock letter, with the deadlock letter you can immediately involve CISAS. If you don't get a resolution letter, then you can still involve CISAS, eight weeks after your initial complaint was received by VM. If you have previously raised a complaint about this matter and have the reference number, that can be used as the start date for the eight week rule. In any CISAS complaint, explain the background and request that VM be required to give you the promised deal, fully backdated, with compensation for distress and inconvenience. Not only does escalation to CISAS cost VM money (free to you, costs of several hundred quid are ALWAYS paid by the company) but it gets your case investigated and impartially heard by expert dispute resolution staff. From published data, the majority of complaints escalated to CISAS, either the company immediately concedes, compromises, or loses at the end of arbitration.
