Does anyone have any suggestions on how this could be escalated, or steps to taken to get this moving along any quicker?
No. And to offer a more nuanced and detailed answer, no. The regulars of this forum have watched in wonder, horror and despair at how VM have managed the pre-pull (and related re-pull) activity for for the past few years. Nobody at VM can help you. Nobody at VM knows anything. Nobody at VM cares. Nobody at VM can cut through their own North Korean style bureaucracy. They may be able to offer a hand-wringing apology, and send an email on your behalf to the mythical "area field manager", who in turn is equally unable to help. They can help your raise a complaint that'll be either completely ignored, or get you a poorly worded fob-off that takes you no further forward.
The good news is your pre-installation work could be done without notice tomorrow. The bad news is that the longest known delay reported in this forum was thirteen months. In some cases VM decide after a few weeks it's all too expensive and they cancel the work altogether (contrary to what you may have been told already). But you'll get no advance notice (of any reliability) ahead of those three possible outcomes. The minor and not-really-what-you-want silver lining to the VM cloud is that you're due £5.25 per day for each day between the original installation date and the actual date (or you cancelling in frustration). Even then VM manage to corrode that silver lining by ignorant call centre staff who don't know the regulations or don't care about them and try to browbeat customers into inadequate settlements or nothing at all, or better educated staff who know the regulations but try an weasel out of the obligations with the local authority permit lie, meaning you need to make a formal complaint to VM, reject their resolution and escalate the complaint to Ombudsman Services.
Or even if it is worth sticking it out and wait for it to actually be installed,
Only you can say, and that depends on what alternatives you have.
and if it is what would reasonable compensation be?
There's clear rules, even if VM don't always abide by them. Note that the compensation is still due if you cancel (up to the date you cancel the order), if VM cancel it's due for a further 30 days beyond the point at which they issue a formal "cease notice" saying they aren't connecting you and won't be paying compensation beyond that 30 addition al days.
