can`t believe the charges getting banded about just for sealing a leak,some vauxhalls have a drain under the battery so that would be worth checking out,if you see water at your passenger door then it may be worth removing the door card and check the membrane is secure and in place and also make sure the drain holes at bottom of door are clear,I for one wouldn`t feather the nest of rip off merchants and see if you can get someone on the side to at least have a look at your problem,good luck
cdc
July 2012