They will bill your insurance company anything from �40 to �75 + vat for the repair ,
They are not magicians and it may well not dissapear , It will put strength back into it however and it should be repaired to an mot standard , if not take it back to them.
Sometimes they may crack when being repaired If they haven't told you the risk you may be entitled to a new w/screen paid for by them .
Remember they said they could repair it not make it worse!!!! certainly a bone of contention and they will back down !! if they havent informed you of the risk !!