Hi! I need some help. Could somebody correct my mistakes In this Formal peace of writing?

April 19
th, 2009
Dear Sir or Madam,
I am writing to complain about the robot which I bought from your company, two weeks ago.
Two weeks ago robot was working quite good, he did everything what was written in the instruction: recognized voices and faces, made 1000 movements, used 20000 words, scheduled appointments, detected persons emotions and made partnerships between human and robot.
Yesterday I recognize that he does not do all these things. I suspect that he fall downstairs.
To sum up, I need you to change my robot to the new one, or to fix it in two weeks.
I look forward to receiving your prompt reply.
Yours faithfully,