I'm not sure what is chowing the battery. Before I started using sonoff my electrician recommend Qwikswitch. They have a similar concept which I believe is also RF. Biggest differences are that theirs is not touch sensitive and has no LED light for the button.
Both Sonoff and Qwikswitch use two CR2032 batteries but the Qwikswitch lasts 2 years. The build quality on Sonoff is much higher though. In the end I went with wired switch.
@DTBA if you want to have my sonoff switch and willing to organise/pay the courier fee I'm happy for you to take it. Mine has two buttons though. PM me if interested. Or if someone else is willing to tinker with it and see if parts of it can be disabled to improve battery life.
