Just to clarify. You are talking about the RV Plus Charge Card as opposed to the My Rewards Card? You are talking about gas discount as opposed to diesel discount?
Why not call the number on the back of the card. I had the occasion to do that about an issue and found them to be polite and knowledgeable and resolved the issue with that one call.
In your case, I'm sure they will need some verification from Good Sam that you are an elite member? By the way, has your membership status changed since you got the card. Mine did and they made the adjustment 2 months after the change.
Tom