Did they deny 93320/93325 due to an LCD issue? I know a lot of the carriers have only specific codes they will reimburse for when billing those codes.
Did you bill these services on the same claim, meaning, the Echo and TEE together? They are not bundled to each other, however, if you billed them on the same claim I bet their system kicked it back. Since 93306 already includes 93320/93325 they probably assumed it was being billed incorrectly and not taking into account there was also a TEE billed; you can still bill separately for 93320/93325.
Not sure if that is the reason. But that's what I think. If it's Medicare I bet it's a delay tactic. They love those!