Why not pop along to your local vehicle breakers yard to find similar year Jazz with correct fittings?
Doesnt need to be a Jazz. 210mm long J bolts are used to secure batteries on lots of cars. Whether the yard will sell them cheaply ,or ask something near the cost of new ones is a matter of luck. May not be worth the hassle
Or you could pop into a DIY store and buy 500 mm of m6 threaded rod and make your own.(£1.82 in Wickes) If the rod is maleable enough to be bent into a hook that great. If not you may be able to sort something with nuts.