is it time to replace my boiler???

Glow worm swift flow120 combi boiler(1995). The boiler
was working fine then stopped, Mr man on this forum suggested PCB board which was correct, thanks for that. engineer came and loose connection on one of components on board & he got it working. He added loads of water, cranked up CH to high & put hot water on full. As pressure was rising towards 3 he removed some water & said expansion tank gone & fan was vibrating so basically bin it!! He said to replace board (£178 + VAT) I told him not to bother so he had to isolate & mark it as dangerous. Thing is it was working fine until he fiddled with water. Was he right? I just felt a bit pressurised to get a new one. Should I buy a new one when money is really tight.