"if anyone officially inquires, there's "nothing to see here; move along"."

If appealing anything, you need to go via a formal paper route, don't just drop in and get narky at the desk jockey. Front of house staff can't just make up stuff as they like, and if they are doing so, then you should seek redress. Apply in letter, for the formal paperwork with which to make an appeal. Return said appeals paperwork with clear details of why you are appealing and why there decision against you is wrong. A signed note supporting your claim from an advocate - some kind of official person would be good, if you are a Christian go to the vicar maybe - but there are also usually charitable advocate bodies out there who can help. Keep copies of ALL correspondence. Retain evidence from post office of posting these materials. Do take these procedures seriously and consider the long term, if your health is going to become increasingly impared over time, you may have to consider rolling up shirt sleeves and ensuring you are in receipt of everything that you may be entitled to receive.