Well I mailed bodycare and they quoted £18 to do the battery on my S210. However having had another look at it today I'm not sure if it needs repairing rather than just a new battery. The last few times I was out with it the display kept going blank, particularly when putting the light on. The very last time, it went blank and lost the date, time, elapsed time etc. I thought the battery had gone flat and the watch had reset, but looking at it today it still has my last six sessions, my totals etc. Weird. I've found the proof of purchase though so will send it back as a warramty repair.
Thanks all.
Paul