JPMorgan Chase & Co. Bank Account Or Service Complaint

JPMorgan Chase & Co. Bank account or service department,

Checking account Deposits and withdrawals California

Hi, my name is - - -, my bank is Chase Checking Accunt. In the date -/-/2015 my bank authorized a transaction of mine without any signature proof, it was with the merchant - that is dealing with -, they charged me $1500.00 from my credit card without any approval from my side. My bank claims that i have already few disputes with other - that scammed me so they declined my request. When i first registered to the site i gave this company my information as it was required in order to open the account, but it does n't mean that they can use this info to charge me when ever they want without my approval. Please advice what i can do here.