This is one of the huge drawbacks with TK; I can't in my wildest imagination comprehend why they can't have a ticket counter air-side. I don't need a visa to Turkey, so it's fairly easy for me to go to the arrival hall and get things fixed, but a lot of people traveling through IST don't have that option and are left with the useless TK CS on the phone.

There is actually a small ticket office at arrival, before immigration (right next to the transit security), but it seems like it's mostly an internal service office for TK, and they do not like customers visiting them (and i't closed between 6pm and 6am anyway).