Hi, a couple of weeks ago I noticed my car was hard to get into reverse (changing gears on the floor), I took it to a transmission specialist, he put it up on the hoist, shook his head and said take it to Toyota. By the time I took it there a couple of days later it would start in neutral as usual but as soon as I put it in start or reverse the engine cuts out. It has now been at the Toyota service centre for 4 days, and they don't seem to have any idea what's wrong with it. They did mention the transmission module seems to have been wet, probably because behind the back seats the car fills up with water if it rains heavily.
 
Any ideas would be much appreciated.

sorry about the late reply. that is quite a common issue with the transmission computer getting wet and getting destroyed. so if the ecu was wet that would very likely be the cause for your issue.

if you replace the ecu please clear out your roof drains this will stop water getting in the storage compartement. pull the side vents out of the side of the car you can get all the build up of dirt and crap out of the vent drains from there

cheers