Well, now, hold on a second. You don't have a Written Agreement documenting this? Why not? (I like the term, "kickback," Maria, and the description as well.)
Now, it may well be legal for a person to double as a real estate agent and a mortgage broker and offer a discount for using bundled services, so long as such affiliation and discount are disclosed and agreed-upon in writing.
But the thing about verbal agreements is that, well, the two parties often have a very different understanding of that agreement.
Here's how to avoid the trap: Make sure your agreements are in writing.