I think give the best of best service for customer.
They have a kind attitude to always.
They are understand the customer.
Here's your corrected composition, Sun. I appreciate your sending it. Please take a look at the corrections below. 
I think give the best of best service for customer.
They have a kind attitude to always.
They are understand the customer.
>>> I think a top-notch customer service agent should always show kindness and understanding toward customers.
>>> OR: Exceptional service stems from showing consistent kindness and a deep understanding of customer needs.