Etihad Airways complaint: poor service by agent and managing staff

3NDOF4 .

im travelling from lahore to dtw via amsterdam and in this flight its almost 3 airlines involved etihad klm and delta
i booked this flight through justfly.com
my baggege allowence is 2 checked bags so i came to lahore airport and was checking in with agent in lahore airport . everything was going well and i gave passport green card so they print out the tag and suddenly he asked where u going to so i told him my final destination is detroit. and then he called his supervisor or manager and didnt tell me anything about it whats going on. so they were talking and then put the note that i cant travel and tore down my ticket . and then im like why i cant so they be like you have green card and your baggage cant go to your final destination which they didnt described to me . later i ve to step in and ask for manager so her name was mehren she step in and told her what happened and she was surprised to and the agent didnt told me anything until i ask and this behave was not good so . she is like we can check u in again without bags i have no choice this and that. but this acomondation wasnt good and i have to travel without my bags. because etihad doenst have contract with delta or idk. but this flight include klm also but no option. this is the worst experience with these airline. feel like almost a mental torture. which cause me alot time at front desk without any help.