[Closed] New account free hosts limit

I've just created a new free Dyn account, hoping to use DynDns Free to set up a hostname to point to my dynamic ISP IP address. However, when I try to add a hostname I'm told I've reached the limit. There are none set up though. Is the free limit now zero, or have I done something wrong? The instructions I had (that came with a DVR I just bought) said there would be an option under 'services' for 'Dynamic DNS Free', but I can't find anything like that on the Dyn website.