I would not wait, march into the manager's office and make it quite clear that you are very upset by this sudden change in scheduling and price. Technically you should be grandfathered in to your price, that is ridiculous that they changed the terms so quickly on you. They knew at the time that you signed up that they would be doing a price increase and not informing you of that when you signed up is contestable.
Get your money back, or fight to be grandfathered into those aqua classes. But now that the schedule is different then what's the bother, you can't take any aqua classes anyway. How frustrating!
“If you try to lose weight by shaming, depriving and fearing yourself, you will end up shamed, deprived, and afraid.” Geneen Roth