if you have internet banking set up go to "utility bills"
it is a little bit trial and error in finding the right part in the drop down menu. we have always paid eletric and telephone by auto pay.
I do all phone top ups on line, and this year paid the car tax online. saved hours queueing at the bank or tax office.
I usually pay the Digiturk yearly, but not sure what or where I will be later this year, I changed back to monthly, but like the water kept forgetting, even though Digiturk sent me a bill online. I went throught the drop down menus, found Digiturk and input my customer number (Abone) and it came up with the 2 outstanding bills to be paid, as I knew how much I owed knew then I was in the right place.
the same by now locating the SU drop down, then look for Fethiye Su and input your customer number.
Like I say trial and error.