This might have something to do with resent closing of BA IST town office?
Earlier this month I had no problems arranging another DONE ex-Turkey with BA IST. Why did you request the pricing in Lira as EUR is now the official published currency for ex-Turkey xONEx tickets? DONE4 base price ex-Turkey is currently 4.358 eur - stated by OW and quoted by BA also, of course. Many FT's have positive experiences with BA IST so I wouldn't judge them just based on this. However, future will tell how things develop after the ticketing office is now closed...