Free charged me 70€ for 4MB of data overseas.

Hello, went on a trip back to my country. As I got off the plane I removed airplane mode to connect to the airport’s WIFI and call my dad via Whatsapp and during a brief moment between me removing airplane mode and connecting to the wifi I apparently used 4mb of data which they want to charge me 70€ for. Is there a way to dispute this charge? I am a student and really can’t afford to waste 70€ for that small mistake