Well yes of course they aren’t going to turn up of 30th, neither are you likely to get any sort of compensation - well not without a massive fight anyway. The compensation is given as credit on your account once you are connected up, so paradoxically, the longer they delay the longer they keep the money and not give it to you you, in fact if they keep you hanging on long enough, until you get bored and cancel then they give you nothing - genius, no?
Actually no, the above scenario implies a degree of planning and intent on VM’s part. The truth, more mundanely, is that the VM installation process does seem to be terminally broken, or at least so riven with corporate incompetence that it amounts to the same thing.
OK seriously, give yourself a hard deadline, let's say next Monday. If nothing has happened then call Sky and cancel the cancellation, even if it means signing up to a new year's or whatever contract. DO NOT cancel the VM install, it might happen or it might not, but if it does, then immediately cancel within the 14 day cooling off period at no cost to yourself. At least then you know that the cable is installed and working should you decide to give VM another try. And even if not, you have the slight satisfaction of knowing that VM have spent money on getting you connected up, for which they won’t get a single penny back.