Originally Posted by SK AAR

TK call center agents are not going to rebook you OAL - they say they can't do it/are not authorised to do so. You have a better chance by turning up at the airport well in advance of your original departure time and ask the TK agents at the airport to rebook you to final destination. Most likely airport agents will be able to and willing to do it (they have much more leeway to rebook pax than call center agents). This obviously provides that TK doesn't automatically rebook you for the next TK flight 4 hours later - then your chance of getting rebooked at the airport OAL will be close to zero (because your new TK flight is not cancelled - and the agents couldn't care less that you will miss your connecting flight as this will have to be dealt with by TK at IST). If TK refuses to rebook you for any other flight than the later TK flight to IST you would have to overnight at IST (hotel and meal will be provided by TK) and take the flight to final destination the next day. Did you check already if there are flights from IST to your final destination with a different carrier on the same date? If yes, you may try asking TK upon arriving at IST of getting rebooked to that flight, even if it involves a different carrier and no direct flights (e.g. LH via FRA or MUC or LX via ZRH) - but there is no guarantee. Good luck!

Added: Would departing from DXB work for you? If yes, ask TK to rebook you to TK761 DXB-IST and get to DXB on your own.