I understand now, the only problem is in the imm57 form I mentioned in my employment history that I was working as an accountant from June 1 but did not mention it in "unauthorized work section" that I worked with no authorization between 1-20 June, which is why I don't want to write a letter just to confuse them.I mean whether you submit an excuse letter or not, there is no need to be worry. Some people submitted and they got their work permit and some people did not submit yet they got their work permit. There is no specific rule. I have submitted and described in the letter that I was not aware of this. And, I got my work permit.
I can understand your feeling now. But, if all of your submitted documents are in line with their regulation except for your ignorance, do not be worry they will not deport you. They are nice and understand us.
do you know any more guys who are in the same situation as me and got their pgwp approved?
Thanks alot for your help.