I seem to recall someone here getting their JW records sent to them (JWFacts?) and I can't be certain, but I think he had sent a similar letter in and they just made a note that it was received and went ahead with the disfellowshipping.
Doesn't appear they care, letter or not.
Edit:
Found it.
He sent in a similar letter, they acknowledged it (in the attached documentation) and completely ignored it.