Simple splits watch

[Big Jon]

Ahhh Gross you've let out my secret about my endless supply of Casios...... I'm still using one that must be 10 years old - I send it to Casio for battery replacement - takes a week to 10 days, - OK it costs more than your local bog-standard jeweller but has a 6 month guarantee (from memory).
Casio Service Centre
Unit 6
1000, North Circular Road
London
NW2 7JD

http://www.casio.co.uk/Support/Services/

good luck!