Unbelievable delay

I am an expat and lived in Dubai and now in Denver. During my Dubai days i stopped using THY due to low quality and delays but the prices were high. Now i sent my mother from denver to istanbul(denver frankfurt- lufthansa, frankfurt to istanbul THY. From USA she arrived to Frankfurt without an issue. She catched her transfer flight- TK1588. They took passengers to the plane, made them wait 3 hours due a maintenance issue, then cancelled the flight, offered an hotel out side the airport- forgot obviously transfer passengers who can not go outside due lack of schengen visa. 3 passengers did not know what to do after hours they placed them to airport hotel. Now they are saying the plane might take off at 10 am... MAYBE!!! The duration between frankfurt and istanbul is 2.5 hours. Unbelievable- if they could not fix the issue they will ask another plane to take passengers. How lousy management!! So the delay can be 36 hours as well!!! Nobody knows... you make the math, i would never ever use this airline again..,