Hi,
I had one in 2 weeks ago with a flat battery after 5 days of being parked up.
He already had a new battery in feb this year, battery tested ok, charging was fine and there was no parasitic drain "at time of testing"

This was being "woken" up with other vehicle remotes - it would stay awake for 2 minutes each time with a draw of 0.50A. The motor was parked up in a public car park and also had a National Tyres depot just across the road, so I imagine that it was being woken up quite frequently !
A new receiver was £169 + vat, cheaper option was to disconnect the ariel from the reciever (tight ass customer !, although I have been informed that he has just purchased a "Marina" and not the morris kind either !! )
Disconnecting the ariel stopped it reacting to "spurious" signals and still gave the existing remote 6ft working distance.
Regards all
Dave

ps - passat, rover 400, ford mondeo remotes all woke this up !