Unfortunately, club's are generally free to charge what they want for use of their facilities, and although the change in price on its face seems unfair, there is unlikely to be any legal recourse, and you may be better off seeking membership of some alternate club, assuming there is one.
If that is not a realistic option, you likely would need to try to garner the support of fellow club members in the form of a petition or similar and try to get the club to change their charges to something more reasonable. Likely you are not the only member affected by this price rise and it may well be that you can secure considerable support if you present your situation to the other members.
My answer would be different if you could demonstrate that they were discriminating against you on some grounds that is prohibited by law, such as your race or religion, but clubs will generally be entitled to charge different fees to amatuer and hobby users of their club, and are otherwise free to set fees as they like.
I appreciate this is not the answer you would would have been hoping for, but it does reflect the law as it applies to your situation.
Good luck and PLEASE RATE MY ANSWER.