+0
He everyone! Could you please help me. I need to write a reminder to a client about the document he promissed to sent last week.

"Hello,
Sorry for disturbing, but we should like to remind you about the NAME of the document, which you jave promissed to sent last week.
It would be great if you will examine it this week or tell us, when can we expect for your feedback."

Thank you in advance.
+0
Even if the client did PROMISE to send it to you, if you want to be polite, it's better not to use that word, because you sound like you're making an accusation. "But you promised..." is an accusation often used by children against their parents :-) Mostly it's pretty good, just a few grammatical errors that I've marked.

Hello, Dear name,
Sorry for disturbing you, but we should (or would) like to remind you about the name of the document, which you jave promissed to sent said you would send to us last week.
It would be great (or We would appreciate it) if you will would examine it attend to this matter this week promptly , (comma here) or tell us, (no comma here) when can we expect for your feedback.

Actually the last sentence might be better rewritten as something like:
We would appreciate your prompt attention to this matter. If there will be a delay, please let us know when we can expect to receive the document.
Comments  
Thank you very much, and now I will not use "promiss" with clients:)