1, I can understand;

2. I understand your feelings very well;

I understand why you are angry. If I were you, I would feel the same way.

4, please don't worry, I understand your feelings, we will try our best to solve it for you;

It is inconvenient for you to happen such a thing, but we should face it positively, right? I know exactly how you feel. Please rest assured that we will find out and give you a satisfactory answer.