The council office for Fethiye / Calis is above the Migros in the centre of Fethiye. Just walk down the RHS of Migros & you'll see steps & that's the entrance.
To pay council tax, you need a copy of your tapu, as no bills are issued. To pay the water, either the bill, which is left by your water meter, or the number on the plate that is attached to the water meter.