driver side seat belt waist anchor faulty

I bought this car from a small used car dealership, where after purchasing this vehicle a week later or so the seat belt anchor kept coming undone. So i had a GMC dealership look at it and they said the seat belt part is faulty, no longer made by GM, and that i would have to have someone put a whole new seat in from another used malibu maxx, I AM PISSED OFF, but i hear of used car lemon law in MN that might cover this serious safety oversight by the dealership that sold it to me.