Weekends still booked up "en bloc"

My wife & I plus 3 other couples, all Club members, decided yesterday to try & book the Chatsworth site for a Friday to Thursday stay in April - NO CHANCE  The weekends there are almost totally booked up all year  Surely there is some way round this situation  I know it's a popular area for walkers but could the Club not keep some pitches free for longer stays?  Does anyone have an answer, I had the same trouble last season with the New Forest site?