We have a similar system with Royal Holidays and didn't want to continue buuuuuuuuuuuut unfortunately you still have to pay the maintenance fees whether you use the points or not. I think you will fine that the contract tells you how long you signed up for and it can be as much as 30 years............yes I did say 30years and when you die this passes to your family. It is a terrible worry is you can no longer use the points or just don't want them anymore. We even went to a lawyer to try and get out of it but they just have you tied up on the paper work. so we are stuck with paying for the next 20years whether we or our family use it or not, and like you the fees are now up to £800 a year!!!!!!!
Hope you have better luck that us at getting rid. Have you tried to sell your points off to someone else as this would appear to be the only way out, although we couldn't sell ours.
Sandra