Fed Up With Fiat

I have a Fiat Punto (1995) that has had something wrong with it since day one. The problem that I am seeking help for has got me so irritated since it has happened only days after it came back from an independent garage where it had four valves replaced because the timing belt slipped. When I drove away from from the garage (after having paid nearly £400 pounds) I noticed that the ECM light was permanently on. I know that it is the ECM light because since I noticed it I have trawled countless message boards trying to find a possible solution only to learn that problems the likes of which I am experiencing are pretty common with Fiats and could be sourced to numerous failings such as coil packs, sensors, throttle positions???..etc, etc, etc. Why didn?t I go back to the garage and get it checked out? It seems like the reasonable thing to do since the problem only started when I got my car back from them after having slipped them £380!! Well?I did but was bluntly told that it is not their problem since their remit was to get my car running again. After much argument I have reached the conclusion that they are not going to do anything about it unless I pay them some more money. Well, after two days of the light permanently staying on I have learned why it should be checked out as soon as possible. There is now a problem with erratic revving, so much erratic revving that I can?t even drive the thing because it just doesn?t stop. Anyone that has had a Fiat is probably aware that as these cars get old they sometimes suffer from this problem but it tends to be transitory, after a couple of seconds of autonomous high revving it stops, and you can continue on your merry way. But now this thing won?t go away, and before I go back to a garage I would like to have some suggestions so that I can go back to them prepared and not like the wet, nodding, idiot I usually am. It may help you to know that the water pump was recently changed and that I have also noticed a leaking (drip-drip more than free flowing) from the front of the car. This mostly occurs when then engine is switched on and the leaking liquid is light blue in colour and smells like anti-freeze. If anyone could shed some light on the problem I would be very grateful.