looking forward your help

Dear all'

I need to claim my medical expense from finance department. I am busy to withdraw by myself .. so I'd like one of my colleagues collect that money on behalf of me.. So she need authority letter from me..

Could you please check my sentense? and Could you give me idea how to wirte better than mine....

"I authorize (Name)(ID NO.) to withdraw my money for my medical expense."

is that right!

thanks for your help

chaw su