Then you're just gonna pay the difference.

你只要出差价就行了。

You are going to have to pay the difference. You understand?

你们得为这种不一样付钱。 听明白了？

That has the same value or less and if it costs more than, you pay the difference.

具有相同或更少的价值， 如果它的成本超过， 你支付差额。

You can change your flight (although you may have to pay the difference in fare), or cancel it and put the value of the old ticket toward a new one.

你可以改变你的航班(尽管你可能需要支付差价)，或者取消它，把旧机票的价值换成新机票。