Contact Citizens Advice, and ask them to refer to Trading Standards in Reading, where VM are based. There's been a string of similar reports of fires and explosions, VM have ignored every opportunity to deal with the problem quickly, competently and professionally.
If you don't get a satisfactory answer from Reading Trading Standards, then ask them to escalate it as a "national, novel or contentious" issue to the Office of Product Safety & Standards. If Reading TS won't confirm that either they are taking enforcement action themselves or passing to OPSS, then say so, and I'll see what options exist in the UK's somewhat fragmented and poorly funded product safety system.
