Contact the hotel.
If the original room type is still available to book, then of course they can put you back there
I don't mean to be xenophobic, and I'm sure it's my problem, but when trying to explain a situation like this to an AI in Mexico, I don't think it would work out. I can speak a little spanish and typically am very patient, but I don't think I could explain why I don't want this "upgrade" very clearly over the phone. The language barrier can be significant. I figured calling Hilton was my best course of action, and I think I will still call back again later today.
The original room type is not available to be booked with cash or points any longer on the website.