I got a Talkmobile SIM which works on the vodafone network.
It is only £1 a month for 20 'free' mins which is great just for incoming and emergencies, I can't find where to get that deal now, but you could try their other SIMs if you want one last try.
If you need a new battery for that handset, here is cheapest at £3.71 delivered vs. £33 at Audi dealer
http://uk.cellphoneshop.net/sllibafornei4.html