For what it's worth:
A cursory review of the USPTO's Trademark Database reveals that
this is the TM Registration for the WORD MARK in Class 36 (for Financial Services) their case would hinge on. They also own the DESIGN Mark which, arguably, you could claim you are not infringing upon since you are not replicating their logo- only using the name (aka WORD MARK). So demonstrate that you aren't using anything on your website that would infringe upon these areas (which, in order to make the likelihood of confusion argument, they would need to say you are):
BANKING SERVICES- NAMELY, FINANCING, CREDIT AND LOAN SERVICES, COMPOUND INTEREST ACCOUNTS, CHECKING ACCOUNTS, SPECIAL CHECKING ACCOUNTS, FOREIGN EXCHANGE, LETTERS OF CREDIT AND TRAVELERS' CHECKS, COMMERCIAL SAVINGS AND TRUST DEPARTMENT SERVICES, AND SAVINGS BANK CENTERS.
And, if I were JP Morgan, I would go back to whoever my intellectual property counsel is and give the associate who wrote this letter a good swift kick in the "I'll take my work elsewhere" ass. Of course there is a likelihood of confusion. That's implicit. You went to school for seven years and that's the only/ best argument you could come up with?
If you really wanted to be a bugger about it, post information about their terrible customer service (which is not covered by their trademark) and if they go after you about it, tell them it's your first amendment right. Make a constitutional law issue out of it. It'll be an incredible waste of money, their resources and time.
The law firm I used to work for tried, and failed (Yes, a LAW FIRM) to do an UDRP domain recovery and trademark infringement suit against someone who registered the name 'lawfirmname'loses.com. This was against a jilted former client who, you guessed it, lost the case.