I have just done my 'roof liner', follow the removal procedure on utube, comes out easy. get a stiff brush and remove all the crappy left over foam, it cost me about $ 90 to do. !.3 mtrs and a can of adhesive. a shop will charge you around the $250 plus mark. i had to do mine to get it over the pits.
Dont bother trying to get all the old glue off. just brush and wipe over with some acetone.
came up a real treat.