Hi there,
I just discovered there are no seat belt latches in my back seat. I just picked up the car last night, bought it used from a reputable car dealer. So, do they have have to install the seat belts free of charge or will I have to pay?
Thanks for your help.

Just hold on and check if the seatbelts fell behind the seat. Also, remove the bottom seat from the back to see if they're down there. It happened to me as well.