I've had the same problem. In my case the Premium account goes back to 2006 and I pay $25 in tier every month but for some reason there is a "problem" with my account when I try to claim the free house LL continues to advertise on the website. I had to use Google to find out how to contact support and then I was sent to a page with information (no links) and got the impression that only billing inquiries were going to get any attention.
I've concluded that SL essentially has no real customer support and continues to tout free homes they have no intention of awarding.
Most of my time these last few years has been spent on the opensim grids -- specifically OSGrid and Metropolis Metaversum. Now that hyperlink is working pretty well I have access to many other grids. If your SL experience is turning sour, as mine is, I suggest you take a look at the rapidly developing alternatives. I run eight regions on my own server on Metropolis and no one ever sends me a bill.