A person who always picks on someone

More formal way of speaking:

Generally speaking, workers in Japan treat their customers more politely than other countries because of our culture. Even when customers are making unreasonable complaints, it is thought that we should smile and grant their requests as much as possible.

However, a customer with whom I talked to today made me considerably irritated. I almost yelled at him. I am not sure how I will get along with him anymore.

Informal way of speaking:

In Japan, we treat our customers more politely than most other countries do because of our culture. Even when customers are making unreasonable requests we have to smile and try to give them what they want, as much as possible.

However, today I had a customer who made me so irritated that I almost yelled at him. Now I don't know if we will continue to get along.

A Person Who Always Picks on Someone

Hi Yuko,

* We try to be consistent in the subject-pronoun agreement. As the subject ("employees in Japan")  is written in the third person point of view, we use "their", and not "our" which is used for the first person point of view instead. 

^ "talked to" is used instead.

When we use "whom", the sentence structure is: (Person that receives the action) + whom + (Person that performs the action) + verb + (additional information).

Example: (The burglar) + whom + (the police) + (talked to) + (refused to answer any question).

(Just as a side discussion, "whom" is used when we would like to emphasise on the object of a verb in the beginning of a sentence.)

I hope this helps you.