Hi Flipper
HMCTS will send you an acknowledgement when you appeal but not the DWP when you send in a claims form. I usually send in claims forms by recorded delivery for peace of mind. If you did not send the form by recorded delivery did you get proof of posting, if it goes missing you can at least prove that it was posted, did you make a copy or take pictures of your claims form?
To put your mind at ease I would contact PIP helpline 0800 121 4433 and ask if they have received your claim.
Gary
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
