I am not sure if the first companies refurbish but its certainly worth asking if they would refurbish yours (18650 7s6p battery pack) or build and install another battery pack for you. Cost wise decent 18650 batteries are around £3.55 trade/wholesale up to £10 retail plus Labour and VAT. so something to bare in mind. Is there anyone in your family who is a sparky or into electronic or is there anyone they may know that could do it. If so you could get the batteries wholesale yourself from Fogstar batteries who only sell genuine stuff, as this would cut the mark up a refurb company would put on them.
http://www.enix-power-solutions.co.uk/custom-battery-packs/
https://www.batteriesplus.co.uk/acatalog/Battery_Pack_Refurbishment.html