I have previously, and this is part of the email that my senator's staffer got from VSC:
" Your constituent filed as an I - Self-Petitioning Spouse of Abusive U.S.C. or LPR (VAWA). Your constituent states she completed an AR-11 change of address. Unfortunately, Form AR-11 cannot be used to change the address on VAWA forms.
Given that this is a VAWA case, your constituent will need to provide a letter with an original signature that matches what we have on file. The letter will need to provide the new address, and state “this is my new Safe Address” or “I would like my new Safe Address to be ____”. You may submit a scanned copy of the signed/dated letter to the Vermont Service Center Congressional Unit. Also the letter needs to list the receipt number of the form(s) the change of safe address applies to or state all immigration matters. "
Now, in my case I've sent in an AR-11 and a letter with roughly the correct wording (I think I wrote something like "my new VAWA mailing address"). After my senator inquired that's when they finally found the letter and applied the change of address.
So what I'd recommend is to write said letter, print it out, sign it, scan it, give it and a privacy release form to your representative/senator, and have the rep/senator give it to VSC, then a few weeks later they can follow up on your behalf. Like VSC is a black hole for any kind of correspondence which is why "ask your rep/senator for help" has become common practice here because by law they have to answer congressional inquiries.
Also, no, they don't give any kind of acknowledgement if they accept the change of address, which once again is why having a rep/senator on the case is a good idea.