@themonopolyman I was an IPEB and FPEB counsel - first AD Marine, then civilian, now as a civilian attorney - and PEBLOs are hit or miss.
@Provis and
@PERS-95 are both correct.
Just remember, the PEBLOs are "owned" by the MTF. So the MTF admin are responsible for the PEBLO's conduct first. That's who you may want to visit first; I say "visit," because I'd certainly go in person. If they won't help, then you have more names to give to the Congressperson, if you go that route. Like
@PERS-95 said, the MSC is actually the person who has direct visibitlity on your case.
All that said, technically, neither the PEB nor the VA are under any obligation to give you a status update on the progress of your case until after you have been found unfit for duty - fit members don't receive VA proposed ratings, despite the ratings usually being done.
This is all to say that it may be worth contacting the IPEB attorney located/detailed to your location; I used to handle this stuff quite often. Every military department handles IDES and LDES case administration a bit differntly. So, although I've never seen anyone change between IDES to LDES, that doesn't mean that it can't happen.
In sum, however, the fact that your case has progressed to the VA proposed rating stage means you would have to convince people to stop a process simply upon your request, which may set a dangerous precident - Service members electing to swtich from IDES to LDES after they already selected IDES would inevitably restult in thousands of wasted staffing hours doing medical exams and ratings for nothing.
Please do not take this as legal advice, as I don't know the specifics of your case. I am merely commenting on the administrative logic and it's necessary conclusion to the questions you posed above. No questions of law were addressed.
