This is standard procedure for the VA. As Sharon stated, you should appeal, based on the mailing receipt you have. Don't lose it and only submit a photocopy of the original, to protect it. Lock it in your vault. You'll win!!! The VA should have your mailing envelope, with the postmark on it, in your c-file.
Personally, I wouldn't use an VSO because they could turn it in late and then you're screwed. jmo
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