How is this done? Book says the key will recharge through the ignition which I've tried to do regularly and over a fairly long journey (2+ hours)! Alas the key still doesn't open the car and the 2nd key is always needed, anyone offer any suggestion or hope in breathing some life into this key/battery??

Think it may be new key time as I don't think you can replace the battery! I got a spare from a independent garage for £120ish

@ mcca

i had the same problem with one of my keys, wouldn't charge or operate the locks and the case was all worn and crap
thought i was looking at £ 250 at stealers but sent it to a firm who replaced the case and battery all in 48 hours for £50 it's like brand new
don't know if i can put up the details on here but pm me and i'll give you their details

you can buy a case on ebay for 5 pounds and the battery too, and replace both yourself like I have