Practice writing for IELTS

I have written this letter for practice IELTS. Could you correct it please? and is there anyone here who can guess how much point this writing can get at IELTS writing section.

Dear Sir or Madam.

Hello, my name is Tom. I am writing this letter to request to attend your tennis lessons in England. I am really interested in learning tennis from renowned coach like you. I would like to enjoy an entire course but I have two reasons that prevent me from participating everyday.

One is that my visa will be expiring at the end of this month. It means that I will only be able to stay here for two weeks and I will miss half of your course. The other is the starting time of the course every day. I have a job for the duration of my visit to England and it finishes at noon on Monday to Friday. So I won’t be able to catch up with a morning exercise.

Due to those two reasons, I would assume that it would'nt be neccasary to provide payment for the entire duration of the course. Would you mind if I asked to refund some part of the tuition? If it possible, could you tell me about it please. My phone number is 000-000-000.
I am looking forward to hearing from you.
Your sincerely
Tom.