We have the same problem. We have a crowd called Broadworks supplying us with cable, they basically get the feed from Sky Digital. All the apartments were pre-wired with their boxes, and there were flyers for installation everywhere when we moved in. €80 to connect all 3 rooms, which isn't bad (even though all they did was flick a switch) and €17 per month, 1 year contract, 19 stations. However...............
1. Despite promises for the last 6 months, they haven't delivered Sky Sports (they are always with meeting Sky to negotiate prices etc.). One guy in the development rings them every Monday, he's very worried that he won't have it for the Lions games this summer.
2. About 2 months ago, we got a letter from the managing agents reminding us that it was against the terms of the leasehold agreement to have satellite dishes attached to apartments (around 4 apartments have dishes). The same day, we get a letter from the cable co. telling us that the monthly fee is to rise to €19.99 due to increased programming costs (no extra channels?)
3. Around 2 weeks ago, we lose Sky One and Sky News. Girlfriend calls the cable co.-they were never actually supposed to be carrying these services, but they should have the licence by Monday-nada for 2 weeks (They replaced Sky One and Sky News with UKTV Gold and UKTV History)
At the first residents meeting, the cable company was discussed. They have exclusive 'rights' to provide cable to all apartments, cos they piped the houses. I think NTL laid cables underground, but wanted some sort of fee from the builders to wire the individual homes (and then presumably a connection fee from each subscriber!), so the builders went with these guys (what do they care, they can still say that every home is piped for cable). I asked the managing agent to find out how long this 'deal' lasts for, and if we could tell them to sling their hook (this was before the loss of Sky One).
A few apartments have Sky dishes (against the terms of the lease agreement, but it doesn't bother me-plenty of worse stuff going on), and NTL would install MMDS (rip off if you ask me), but this requires an aerial on the roof or attached somewhere (also against the terms of the lease agreement).
So I don't know why Sky have to ask the builders, have you not signed the contracts yet? I would say they would do it when the apartment is officially yours, but it will more than likely contravene the terms of your leasehold agreement.
If you have to go with this other cable co., I would be wary. Service is patchy, and you never know what channels you'll have from one month to the next. It is bullsh~t that we don't have a choice, especially given the crappy service we've been getting.