E-mailed statusmatch@radissonhotels.com, sending a screenshot of my Hilton and Radisson membership cards. They replied within an hour asking for me also to send a screenshot of my Hilton online account home page. Once this was done I was upgraded within a few minutes. One thing to note is that I first tried with my IHG Platinum status, but they refused to match that to their Premium tier, saying they would not match IHG Platinum to any tier.