Send them an email--there is a contact us location on all these sites. In your first email ask how you can be given equivalent status for your Marriott achievement and offer to provide documentation.
They asked me for proof and I forwared (by fax as I recall) my most recent statement from MR. It may not always work but it did for Shoeman and myself. Good luck and let us know what happens.
In addition to Stepping Stones advice, I would offer this idea. I actually booked a night at a Hilton and worked my magic with the night manager at checkin. He became my partner in getting the status. In fact, after pleading my case with him, he took my info and days later my Hilton status card showed up at my house. good luck.
Sounds like a good idea to get status with other providersASAP. I am going to lose platinum this year, not traveling as much. So getting top level at another provider makes sense since Marriott is not going to honor anything for me next year.
I wonder if next year as a HH top level will Marriott then gicve recip back to me to stay Platinum?