Sunday, March 9 - my Gold membership expired yesterday. Today, the code for three months of Gold worked! So did another code I'd bought for an additional year of Gold. However, the codes for the free games still won't work. I've replied to the email yet again, so we'll see if they make good.
If this lasts another 8 days, it'll be a full 3 months since this began.
I know it's my 3rd post in this thread (sorry), but it's VERY unsatisfying. By my count, you can make like 10 different variations, and that's it. You choose from set stuff, like dimensions, walls, grass, dirt, seats, and location.