Hi fm,
I am a little unsure of where you are in the process at the moment, although I think it is PIP you are talking about?
If the decision on the claim is not what you hoped, your first step would be to submit a request for a Mandatory Reconsideration. There is a sample letter in the PIP appeal guide.
If the MR does not go in your wife's favour, the letter will contain a form that you must then send to the Tribunal Service for your appeal to be accepted. Again, the PIP appeal guide will talk you through the process
PIP help for claimants If I have totally misunderstood, please reply to this and we will do our best to help!