This was actually my first BAD encounter with the Chairman CSRs. I had a one-night stay in Glasgow booked through hotels.com (couldn't get availability ANYWHERE as there was apparently a parasite conference during the week and then a huge international piping festival that weekend.) They booked me into a full hotel; after much trouble they moved me to a (admittedly much nicer) hotel. They agreed to pay cab fare both ways (about £20 each way) as well as refund £20 of the room rate. Hadn't seen any such thing a couple weeks later so I emailed them, no reply.

At that point I called the Chairman CSRs, as my due date was approaching in a couple weeks and I certainly didn't want to pay £60 of charges that were supposed to be refunded to me. They told me they actually could not dispute that until I'd gotten a written/email confirmation from hotels.com, or had at least tried to do so. So I ended up not being able to dispute the charge yet.

Amex will let you dispute anything, for any (reasonable) cause, at least temporarily until the dispute clears of course. I was told by the Chairman folks that they had a checklist that they had to go through to determine whether or not to open a dispute, and I'm guessing this is the same as with regular Citi.

It seems to me that they should at least put the charge in a pending dispute status and put the charge on hold until the dispute is fully opened. I'll have to mention this the next time I speak to them.