wi-fi cards

Its not often that I use a laptop whem away in the motorhome and when i do its normally when im on my own as this enables me to "skype" the family and keep in touch. Last weekend however  I had to go on a solo trip and stopped the night  at a club site with wireless facility especially for this purpose. On my last solo trip I bought a £10 card and only used 50pence worth so i stored the card away for future use. On this night however i tried to access the club wi-fi 3 or 4 times but i couldnt get a connection. Eventually after much head scratching I noticed on the card "valid for 6 months". By now however the reception was shut and so the whole point for my choosing the site was a waste of time. The reason I write however is that I felt cheated and conned, why has the card got a time limit, surely if you pay for £10 worth of air time thats what you should get. Is it just me or do other members feel this is unfair?. Sorry just had to have a moan, disgruntled of cornwall!!!