Not sure if this is the correct place for this kinda complicated question (moderator please let me know) but here goes:

In January 2011 I booked AUS/EWR/EDI/EWR/AUS in coach for travel in late August 2011. At that time I paid $500 each way plus 20,000 miles each way for an upgrade to BizFirst - knew I was waitlisted but was ok with that. Now have confirmed upgrades on all legs except EDI/EWR return (the other upgrades came through in April - and based on seat availability I'm optimistic that EDI/EWR will come through). Also at time of booking I paid APD of $95.31 (presumably the 60 pounds collected by her majesty's government on a coach ticket originating in the U.K.), which was included in the quoted ticket price.

Yesterday I happened to look at my AMEX statement on-line and noticed that CO had, without any notice to me, charged that card $195.85. When I called, the rep told me, after a long hold while he researched, that it was a UK tax for the flight to EDI. I guess he was half right- it's a UK tax for sure, but on the return as I understand it. And since I'm already upgraded for the domestic connector on the return, the tax still applies as I read the UK regs. But it seems to me that CO messed up in several ways:

1. They didn't tell me about the additional APD tax at time of requesting the upgrade. I'll let that one go since it's probably in the fine print of their contract of carriage somewhere that they can collect any taxes they need to, up to and including at the time of travel.
2. The charged my AMEX in August without any notice to me. That seems pretty underhanded. Again, maybe it's buried in their contract of carriage, but still not right to do so without notice IMHO. (By the way, the additional tax collected does not show up in my receipt when I look at the reservation on CO's website.)
3. CO appears to have charged me the full APD for BizFirst of 120 pounds, without netting out the 60 pounds they already charged me at the time of booking. That just seems to be an error on their part, but based on my unsatisfying conversation with the phone rep yesterday, I'm not sure what to do about it.

Input/guidance on how/who to deal with at CO welcome. And if I've missed something and CO is in the right on this, please let me know that as well. Thanks to all.

What about disputing the charge with AMEX? Provide them documentation that the mileage upgrade is advertised as copay+miles with no mention of miles and it should be a very easy case.

FWIW, I got upgraded to and from LHR on UA metal this summer and was only charged miles (I was in full Y), no extra taxes collected.

I thought UK charged an extra tax for "premium" travelers?

They do...unless you're operationally upgraded at the gate. I didn't pay J-class APD on several such occasions although the tix already sort-of-contained Y-class APD.

Thanks for the feedback. I have a long layover at EWR on Saturday and will see if the agents at the Prez Club can help.

heh