I didn't get it in the mail. I got it twice last summer by email and passed on the upgrade.
A few days ago I logged into my account and saw a banner inviting me to upgrade by business gold to Platinum. This time I did the upgrade, because my personal platinum is about to run out and I didn't want to renew that.
A day or so after doing the online upgrade, my online account showed that my business gold card was now a business platinum card.
I then made a purchase with my business gold card (still waiting for the new platinum card to come in the mail) and two days later was credited with 25,000 MR points.