Ok as you may have found out looking around this board is now obsolete. So you will find most spares shops wont have this as how spares shops work is when you order the part they order it direct from the manufactory so as they don't have it the spares shops wont be able to order it.
However I have found the part as a refurbished board on Ebay which someone it selling so if you have ebay they you can order it from them.
Click here for the ebay part
Hope this helps you but im afraid you wont get a new board from a spares shop anymore.
If you need anymore info just get back to me.
OK, that's very helpful. I'm just confirming with the eBay seller that he regards ***** ***** he is selling as a valid replacement for a BNT72X0353 Main PCB in a De Dietrich DTI304. That done, I'll rate as excellent.
No worries that's fine.