help with supporting letter

Dear All,
I've written a letter to support my dad's visa application form. There are few tricky things to explain clearly on the letter and I have done that best to my knowledge. English is not my first language and it was the first letter I've written in English. So I would be very grateful if any of you could have a look and point out the faults and help me correct it.
If you can help, please, please pm me so I can pm or e-mail you back with my letter.

Many, many thanks.
sam

See also Four (Easy) Steps to Better Writing (pdf), a handout based on Style: Ten Lessons in Clarity and Grace.

Making Sense > pdf.

The the impotence of proofreading.

GRAMMAR AND STYLE > Concise is Nice

4 Tips to More Concise Legal Writing

How to write clearly

Don’t send an angry letter! The Lost Art of the Unsent Angry Letter

Resolve a dispute with the Home Office through the pre-action protocol