Baxi boiler question.?

I have a Baxi boiler that was supposedly faulty due to a pump problem, the eingineer came out to look and replaced the pump. When the job was finished he turned on the boiler and found that there was still no water. He left the boiler on which was heating nothing but the boiler internals. The engineer then went to the tank and stuck some sort of pole down the pipe and found there was a blockage, he poked the pipe through the block which in turn let the water through to the boiler. As you can imagine by this time the boiler was roasting with no water in it and as soon as the water got through it burst something and came shooting out the front of the boiler. I have been told that when the new pump is fitted he should have bled the system allowing water to get round the internals of the boiler before igniting it. Before this happened there were no problems with the boiler leaking or anything else untoward. The company are now saying that the fautly pump caused the damage to the boiler?