The most recent news update I'm aware of was a news post in March indicating that they attempting to push a Windows Phone update through certification; however, Lumia 640 was still broken, and they were investigating why.
I'll see if I can find more information on what has happened since.
My understanding is that the crash bugfix (for all but Lumia 640) has been submitted a few times into certification, but has yet to pass said certification. From what I hear, that isn't necessarily related to the fix itself, rather just how everything fits together (Hardware and Software). They are hard at work with clearing those obstacles on both sides of the issue. Noone expected nor desired for it to take as long as it has. If it had been simple and fast and easy, then I would have to suspect that - between Microsoft and 505/CG - they would have found it.
Regarding refunds: On any platform, those are all required to be conducted via the platform on which the game was purchased (i.e. Steam, Microsoft, Sony, etc). That is a matter of policy with those companies.
I totally get why people are rightfully upset - its been broken for quite a while - but that doesn't mean that fixing it hasn't been a priority behind the scenes. I can 100% guarantee you that is has been - its one I personally push on multiple times a week.
So, hang in there a bit longer if you can....
Cheers