if there's no sign of Surpass on the original invite, then you will probably have to keep pushing with Hilton rather than Amex (if it was Surpass and you have somehow been downgraded to regular no-fee then you'd need to pester Amex).

they seem to be really pushing these 'gain/reclaim status' promos - i received a 'stay 7 times before June 30' one the week i fell from Diamond (as did my wife, even though she'd only been Gold anyway), and i wouldn't be surprised if their CSRs don't really know about all of them (nor if i have hassle trying to get mine back with only the original flyer as proof).

let us know how you get on after the higher review.