Rapidmumbai

Hi, Any ideas what may be causing this would help. A few weeks ago I reversed a bit out of my garage, and when I stopped and shifted the Automatic Gear Shift down 2 levels from "R" to "D", the gear shift clicked into D, but the car behaved as if it was in Neutral, but the light on the gearbox and the dashboard still showed "R". The gearshift would still go back and forth and click into other gears like N, D and S, but the light remained on R, and the engine would rev like in neutral. However when I shifted the gearshift into P, it got stuck there (light still on R) (car still behaves like it's in N) and wheels are not locked (car can be pushed). However the car cannot be started again because it probably thinks it's in Reverse? I've sent the car to the repair garage and they spent a week fixing the transmission which they said was " low on fluid" which may have caused this. After getting the car back yesterday and driving it for 2 days the exact same thing has happened again. I'm not sure the garage knows what they are talking about? Any ideas??? Thanks