I usually just phrase my disputes somewhat vaguely, leaving Chase to sort it out with the merchant. I usually contact the merchant first and give them a few weeks to work it out before disputing.

Something like this:

"I provided card information to the merchant to provide payment for goods or services, however, I did not authorize the merchant to charge me XXXX USD on XXXXXX date."

I suppose it's kind of disingenuous because the wording makes it seem like the merchant wasn't authorized to charge at all, but it usually works to get the chargeback issued so the merchant is forced to respond.