Depends, depends- did you get a firm, fixed quote for supply and fit based on measurements you gave? If so the shop may have sent out extra packs to allow for waste, errors etc. Those packs not used are then returned- you haven't paid for them as such, only to have a given area floored, which was done, as per the quote you got. Hwever, if they gave you a quote based on the number of packs required and were charging you based on the number of packs used (as advised by carpenter at the end of the job) then that is a different matter altogether. You need to clarify this important distinction before proceeding any further.