If you are absolutely sure that you did not receive the free Beta gold, please create a ticket and let the support have a deeper look into the issue.
However, I can remember quite well that I also created such a ticket long time ago. In my case, I had the check-box for the automatic extension of the advisors activated in one of my beta worlds, and in the second the free beta gold came in, those advisors swallowed it and extended their services without even asking me first...^^
Thus please check whether this check-box in the advisors´ window is activated in one of your Betas - since it happened to you repeatedly, I would bet that that´s the reason for the "missing" gold.