01
The service is too slow.
服務太慢了。
A: Can you tell me what's wrong, sir?
能和我說說有什么不妥嗎，先生？
B: The service is too slow and the dishes are served cold.
服務太慢了，菜都涼了。
A: I see. I'll report it to the manager.
我知道了，我會把這事告訴經理的。

02
There is too much salt in the soup.
湯太咸了。
A: Is everything to your satisfaction?
您對飯菜滿意嗎？
B: Yes, all the food was delicious except that there is too much salt in the soup.
是的，除了湯太咸之外，所有事物都不錯。
A: I'm so sorry for that. I'll take it to the kitchen and get you another one if you like.
真對不起，如果您愿意，我拿到廚房再給您換一下。

若飯菜質量有問題可向服務員提出意見。還可以用“There's something wrong with...” 表示“某事或某人有點兒不對頭”
The meat is underdone.
是說肉沒熟。而overdone則是“過頭了”
I'm afraid this is too salty/sweet for me.
我覺得菜太咸/甜了。
That's not what I ordered.
那不是我點的。

要提意見應該說：
I want to make a complaint.