hi i have a saunia duval semia f24e boiler its just about 5yrs old the boiler pilot light if thats what it is fires up and goes off constantly making a blowing banging noise my rads get luke warm and not much hot water the temp only gets up to about 22 26 if im lucky can anyone tell me what the problem is how much to repair and if it would be better to get another boiler PLEEZE HELP i dont want to freeze this winter