Well, first of all, the United e-certificate is USELESS sometimes. Many people don't know that you are only able to use the e-certificate on certain booking classes. Let's say you see united.com pricing LAX-JFK for $212.00 roundtrip. When you use your e-certificate of 150 to book that flight, it does not necessarily mean that your after certificate price is 212.00-150 = 61.2. Sometimes, you can only book a more expensive fare - perhaps B at 569.00 and in that case your price after e-certificate is 569-150= 419.00 which is more expensive than if you just don't use the certificate at all. I know, I know, STUPID. So, I don't know if that full price was actually the price you were supposed to get AFTER applying the discount?

As far as the credit card issue. I would call and threaten to CANCEL. This works like a charm everytime with every credit card company. They will WAIVE your fees, give you bonus miles, whatever it takes to save you as a customer. Say, I am calling to cancel my card and they will ask you why. Then say I have been nothing but a valuable customer to you but because of this little tiny United issue I was charged 37 and I am a college student and blah blah.

One time, I called to cancel a credit card (MP), and they transferred me to a "specialist." He offered 1500 bonus miles if I did not cancel the card. I declined. Then he asked me, "other than the 1500 miles, what can I do to make you keep your card?".....Let's just say I fully took advantage of the situation

They will waive it.