The translator has done a great job in disguising the real meaning of Chinese. 改签=改+签=changing the original contract and signing a new one. I guess he might be trying to avoid saying the original one is incorrect.

The combination of Chinese phrases are so flexible that some of the foreign learner can't catch the correct meaning exactly.“改签” is a combination word."改“ is not only a verb but also an important act which means "change",while "签” is a basic consequence in this context.You should have put the emphasis on the former"改“.In the Chinese grammar,we usually emphasize the "crucial act" in the combination words like this.Actually,she will sign you a flight but she's about to change the way right?

If you need to change your ticketed flights, such as the dates, destinations, or times, your ticket must be reissued. In most all cases, airlines will charge a fee for exchanging a ticket. 改 = change 改签 can be used for train tickets too..if you want to change the date or the train number.. also it can be used for visas...cause visa means 签证...if you got one and you want to change..you can 改签..

Haha, you are right. Don't be fooled by its look.

Wow ~ why didn't I think of that? It's basically "re-issue", as you say, Fenton. I should have guessed from the “改” part.