Assuming you had your car running when you jumped the gfs R400 it was the alternator in your car supplying the power to the 400.
You can get booster packs from anywhere that does chargers -
This one is from as little as £28 inc postage on an eBay auction, this is a BIN at £35 -
http://cgi.ebay.co.uk/CAR-BOAT-JUMP-...item414b5c8225 or Halfords do it at £50.