I have been to one, when I was refused with my first visit visa one of the gay people outside VFS Makati fetch and took me in the next building where agencies for UK visa were based. They were the normal agencies that you will see in their unfirom at VFS doing their job. They asked me to pay them PHP 25k-35k for visit visa and I dread to think what will be the cost for the fiancee visa and that was way back in 2011. I personally asked the lawyer/owner bloke if I get an assurance that my visa will be granted if they handle it and he said clearly "NO". He said they will only prepare the paperwork but it will all depends if the ECO will be convinced.

So, yes even if you go that way it doesnt mean that your application will get approved but your choice anyway. Good luck with the app.