potterton performa 28 ive got hot water but no central heating?

i have just had a potterton performa 28 installed brand new from the box but bought 3 years ago i have got drawn hot water but when i switch to the central heating the pump runs,,,the burner ignights but goes out after a couple of seconds,,,my installer a family friend has only just become corgi qualified and has been waiting over a month for his official reg number hence potterton will not talk to him yet ,,,i have had no central heating for a month and we are all freezing,,,,help please