Go back and read the advice given by @japitts about taking the matter to adjudication. You're going round in circles with VM, if you want the matter independently reviewed then that is the route you need to take.
The automatic compensation is not the limits of what VM can be liable for, it's merely the minimum they've committed themselves to. Under the Consumer Rights Act 2015, any service must be supplied with reasonable skill and care, so you have statutory rights that then lead into rights of redress including compensation or release from a contract where those are appropriate. Also, under industry regulations VM are supposed to take complaints seriously - the Ofcom Fairness Commitments are a good summary of what you can expect, and can be the basis of structuring a complaint and request for compensation if that's what you're after.
In escalating a matter to CISAS, you need to clearly explain the problem, describe your contacts with VM and their responses, include any instances of rudeness, being cutoff, broken promises either to resolve the matter or call you back, and state clearly what outcome would resolve the matter for you. CISAS are good and independent, but you still have to make your case clearly.
