I'm afraid the answer is that, with most joint mortgages, each person is responsible for the WHOLE debt. In other words, they are well within their rights to chase one person, or all of them, as they see fit.(posted 8277 days ago)Typically, what happens is they locate one person and stop there - after all, why should they expend any more effort in finding someone else when the law doesn't require them too.
Personally, I think this stinks, but they're well within their rights.
I trust you've issued SARNs against the lender and their solicitors. Similarly, don't fill in an Income/Expenditure form, don't speak to them on the phone, do everything in writing and send it all recorded delivery.