How to get screwed by 3rd Party body shops in India

It seems to me like I have spent the last 18 months interviewing in Chennai and that's not far off the facts, with issues with some of the developers we have actually hired, ranging from them not being developers at all to them simply not being up to the standard we require.
However the current issue we have is becoming a real pain and I am sure that others out there have come across this. It seems to be that our management is very keen on getting people from a 3rd party body shop, not a specific one as we have now hired from 3 different ones within the dept. In the past 3 months we have interviewed 3 people from this one particular company, 2 of which have been fine. In both these cases we have reported back to the parent company that we would like to get this candidate on board, in both cases these are Notes Developers but they also have team leader or man-management skills to head up the team in Chennai and take some of the day-day management away from me. Anyway in both cases we have had positive comeback from the company and then nothing, followed a few weeks later by the reporting back that the person wants more than we currently offer, eg. come and work in the UK etc. and consequently they are not joining the contract house. This after my company has given them an HR interview in Chennai, we give them a telephone interview from here in the UK, a technical test etc etc etc and we then find out that in fact we are interviewing these candidates almost on behalf of this 3rd party company who them come to us to try and get more if that is what the candidate wants. Sadly enough this usually never works as we don't want to bring a contractor over to the UK for 3 months (did this once at the cost of £4k per month on top of salary, where did the low cost go) where as if he was an employee of our company it would be a possibility.
We are still going through pain with this situation and I can't really see how we can get round this, one of the problems we have is that the kind of candidate we are looking for doesn't want to work for us and if they do we can't get them the kind of salary they want and while this perpetual cycle continues management are happily under the impression that because they have allowed you to recruit for a Developer that that will actually solve the problem even if you aren't actually able to find a competent Developer based on the salary they will offer in this Low Cost Center.