It is not true that Baxi are no longer in business.. They are indeed a flourishing business.
"Baxi is part of BDR Thermea, one of Europe's largest manufacturers and distributors of domestic and commercial water and space heating systems. It employs 6,400 people throughout Europe with a turnover exceeding €1.2 billion."
Here is a link to the Baxi Customer Support Website http://www.baxi.co.uk/customer-support.htm
You can call Baxi Customer Support on 0***-***-**** and give them the model information from your boiler.. They will tell you what stocks are available with regard to parts.