GROUPON /CastleMartyr Hotel

I Booked one of the Groupon deals for a Weekend break and meal at the Castlemartyr resort. The voucher I purchased was the 4th sold I immediately called the hotel to make my booking . I was asked firstly if I was "using one of them vouchers"?? I was then told that there were no weekend availability but midweek only there was clearly some restrictions on the voucher ,but the weekend of nov '23rd and dec 21st were eligable for booking . I contacted Groupon and they refunded the voucher relatively no problem ,but this was after I had contacted my wife regarding planning a weekend away and then having to cancel it . Whats the point in advertising these?do they hope some people will just not look for refunds . I ended up booking Fota Island on there own site. After the way I felt scammed I feel more so By Castlemartyr hotel I will not be visiting them any time soon.