Owning your own home

My sister has put in an offer on a flat and been told by the agent that if she goes with their mortgage broker and conveyancer they will reduce the price by a couple of grand.

I know a couple of people have mentioned this kind of thing up the thread, but does anyone have direct experience of doing this? Is it really dodgy or just a bit underhand? Any pointers to pros and cons much appreciated.

From what I gather, it's pretty common.

My colleague mentioned doing it without any trouble. I didn't because I'd already set up a mortgage with a recommended fin. adv.