Air Serbia Refused My Stroller on Return Flight Despite Allowing It on Departure

We bought a flight ticket from Airserbia Airlines. Although they did not cause any problems with the stroller on our flight from Istanbul to Serbia, they stated they could not take it on the return flight because it was not in the luggage dimensions. So how did I get to Serbia with this stroller? Unfortunately, friends, if you plan to fly with Airserbia, you need to pay attention. The same airline is very helpful on the way out and a harsh tone that we cannot take it on the way back. Especially at Airserbia's Nis airport, the counter attendant also manipulated the security point so that it would not be taken. It is a difficult situation to understand, if the security point did not take the stroller, I would say it is an airline problem, but the counter attendant provoked the incident on top of that.