Replacing 2002 mustang seat belts?

My Ford dealer wants over $200 labor to replace the seat belts (not
retracting), and he says he has to remove the back seat and then
remove the plastic moldings in both sides of the rear where the seat
belt retracts into.

I think I can figure out how to take the seat out (I hope), but, if
anyone has any pointers, please advise (the back seat folds down to
expose the trunk).

As to removing the side molding, I haven't a clue how it is held into
place - does anyone have any insight for me? I don't mind doing the
labor myself, but, I am lost as to how I go about it - I don't want to
break something.

Thanks for any advice anyone can give me.