On a recent trip I had a multi-stop ticket. I changed part of the route to visit Shanghai. Before doing this I called Virgin Atlantic 3 times to check the cost of changing my route, to change it and to arrange payment. All done, I continued my trip, flew on to Shanghai and spent a month in China.
At the end of my travels, catching my flight home I arrived at Shanghai airport to be told that in addition to the money I had already paid for changing the route two months earlier, I would now have to pay costs for taxes and admin, in ADDITION to those I had already payed earlier to them. Failure to pay this meant I could not catch my flight. Failure to leave China meant I would over stay my visa and would be denied re-entry to China. I had paid US$100. The additional fees were MORE than $140!
Now, regardless if the fees are fair - the problem is I spoke to them three times before making the changes to my ticket and asked three times for the full TOTAL price of making these changes before considering doing so. I then proceeded to make the changes based on the price. I also went to the offices in Shanghai to make the payment in person and for a fourth time they failed to inform me there would be additional costs.
I complained to Virgin Atlantic. My first reply was a mere "we'll do better apology". I wrote again saying this does not suggest the comprehend the severity of the situation - that I had to use a credit card I had for emergencies and which in 6 months of travelling I had never had to use. They had left me totally unaware of these costs and put me in a dire situation. They also had me change my flights on the premise of a false price, and made the mistake not once, but 3 times before I proceeded to change.
After several mails, they offered me 5000 airmiles - which obviously requires I join their loyalty program.
I now live in Shanghai and I will be flying London - Shanghai with BA in the future!
See also
http://www.auc.org.uk/ The UK ombudsman if you, like me, have a serious gripe with an airline.