My car is automatic and I was having problems with my gears not coming down from fourth gear automatically, so had to do it manually. The service light also kept on coming on and staying on even though I had recently had it serviced. I took it into the garage where they first thought it was the speed sensor. After replacing the speed sensor, the same problem occurred. The garage then saw that the transmission fluid was not the right color and concluded that water was getting into it. They drained the transmission fluid and replaced it, but the problem still persisted. I was then told by another source that I would have to replace the radiator and transmission. I have been on a few forum sites, where people have had similar complaints, which they have attributed to an Astra fault.