Thermacon Boiler?

Hi there,
I have a wall mounted Thermacon and its started locking out. Its dont this before a few years ago and a chap fitted a new pump and it was fine. Its started doing it again and a different engineer came out. He removed the black panel on the front to reveal a charcoal box and told me it was all burnt out and we would need a new bolier - is this right? Sorry - I cant be any more specific. I cant locate the exact model as it doesnt seem to be anywhere on the unit. Does anyone know how I find the model number by chance? Thanks loads