CC Wi-Fi Cards & CC Affiliated Sites

We have just returned from the bank holiday weekend at a CC affiliated site.  We had a great time and the site is up to their usual excellent standard.

What was not so good was the fact that my CC Wi-Fi card would not work on their system :(.  If I wanted to use it I would have had to purchase another card, more expense, for only a couple of days usage and we do not plan to use that site again this year.

Now I appreciate that I may have missed the small print about this fact or indeed been a little niaeve about this but I would have thought they could be usable in either venues without too much hassle.

Has anyone else had the same experience?