how do i write this letter?

Dear Chief Engineer!
I have been working in this society since May 2011. I am availing the facility of staff residence at staff hostel in Ravi block. Since Oct 2011 I have been asked to pay all the utility bills (e.g. Electricity & Gas bills) by myself.
It has come to my notice that all the other staff in the same building and the Engineering branch staff that is also availing the residence facility in staff quarters in Dc Colony are not paying any bills since their appointment. While we all have contract on same terms & conditions. (Proves of this unfairness is attached).