giving someone permit to do stg letter

[Özge İnce]

Hello
I ve been searching for more than 2 hours for a formal letter in which is written a permission given to someone. I want to give my permit to my friend so he can get my money which I could not get from someone.. but I have no idea how I can write it in formal way.
Please help me..
Regards

[Anglika]

I hereby authorise xxxxxx to act on my behalf in the matter of recovering the debt of [the sum of money] owed to me by yyyyy.

{your name, and the date}