Turkish Airlines Flight Cancellation Issue

THY caused me inconvenience. I bought 6 round-trip tickets for my family and me from London to Istanbul with a connection to Şanlıurfa. Our outbound journey to our hometown was smooth. However, one week before our return, THY informed us via message that our Şanlıurfa to Istanbul flight was canceled and rescheduled for the same evening. They mentioned that we would not be able to catch our same-day Istanbul to London flight, and I was asked to pay an additional ₺45,000 to book a later flight from Istanbul to London. Despite explaining multiple times to the responsible THY officials that this confusion, which was not caused by me, led to financial and emotional disruptions in my work in London, they insisted that the fault lay with the Civil Aviation Authority, which canceled the flight. They stated that THY, which claims to be one of the top 5 airlines in the world, could not cover the penalty or the costs, leaving me inconvenienced.