Can anyone advise on my boiler problem?

I have a Potterton Profile 80e and the burner keeps blowing out straight after ignition...the flame is really high with the bottom centimetre of it blue and the rest of the flame (about 4 inches) red.. and within about 3 seconds of it lighting it goes straight out.
I am living in France and due to this Baxi potterton will not advise me as i am not a corgi registered plumber and as my fully qualified plumber is french they will not advise him either and he does not know what is causing this problem. PLEASE can you help and advise
what would be the cause of this as i currently have no heating. Thanks
Carol