Re: advice needed
a write of mandamus is essentially a lawsuit against CIS, dept of state, and all involved to make a decision. The decision may not be a ‘yes’ …they may come back with a ‘No’ but it essentially forces them to sort the mess out and not drag things on any further.
I would suggest you look up some immigration lawyers in your area, google if you must and go talk to them about your case. consultation is usually free and they can tell you if that is an option.