Worcester 28i junior boiler - please help!?

Can't get boiler working as it seems to keep cutting out. Have got model (approx 5 years old never had a lot of problems before) as above and have tried blowing through the red and white tubes as per previous answers, but no long term joy. Red light flashing and light going on only on occassion. Have callled various engineers and nobody available for nearly a week. So any help truly appreciated - have young kids and no hot water so it's a real problem. Please help