Longer wait for refund

The thing you need to consider is that VM’s reputation for customer service is already so far down in the gutter that daylight is a dim and distant memory - they regularly prop up the rest of the ISPs in OFCOM’s annual tables of customer satisfaction. No point in threatening to expose them to anyone else, everyone else already knows, there is nothing, absolutely nothing you can do to damage their reputation any more.

Officially they should provide the compensation within 30 days of you being connected up. After that time, if it doesn’t appear, then you start by making a formal complaint - best do it in writing to their Sunderland office (address on the website, somewhere). Now this complaint will go nowhere, but it is a required pre-cursor to escalating the issue to the Ombudsman service for third-party adjudication.