Karate school contract price increase

It entirely depends on what the contract says.  Does the contract allow such a high increase?  Is the contract vague or clear?  (Did you read it before signing it?  You should have.)  In some cases, if a contract has clearly unfair terms that are buried in the fine print, those terms can be determined to be "unconscionable" because they are unfair and you were pushed/coerced/lied to into signing the agreement.  If there was lying involved, then you may have a claim under the Florida Unfair and Deceptive Trade Practices Act (FUDTPA).  But it all depends on the terms of the contract and the facts and circumstances of the situation.You can direct AMEX to not pay the charges, and then you will have to pay each month, if you pay.  You can try to negotiate with them . . . agree to pay the increased cost in exchange for shortening your contract.  You could choose to break the contract, but there may be consequences to that, such as sending the account ot a collection agency, negative entries on your credit report or even being sued.