I LOVE recovering condemned boilers. If you've been told by another technician or British Gas that your boiler is old, dangerous and cannot be repaired but you just don't believe it, then you may well be right. Especially if they seem terribly keen to provide you with a quotation for a NEW boiler.
By all means contact me for a second opinion. I just might be able to get parts after all for your apparently dead boiler and give it a new lease of life.
Don't bank on it but there is a significant chance.