Tinkmiste

Hello
Ive got a 1.5 diesel dynamique (2001)
It is cheesing me off, for starters when i turn the ignition on the immob light flashes franticly and then wont turn over, iv been told to solve that take the key out, lock & unlock which seems to work, but sometimes the heater light doesnt come on thus not turning over, or stays on, THUS not turning over, and sometimes it is just decides to do both after each other, i just keep turning it off and trying again and it usualy works after a few goes, but this morning i went to my car 7:30am drove a mile home no probs, went back to car at 8:05am and it took a good 20 mins of turning on and off before it started so i drove it to a garage and suprise it was fine and dandy when someones looking! but i explained and they said its pointing towards the ECU if its as random as it is, i used it the rest of the day on and off no probs, please tell me its not the ECU , as i might have to lay off the alcohol in order to save up!! sory 4 the long message.
Thanx