Well same thing happend to me last week at the Frankfurt airport. And I last night contacted the airport, but this morning I went searching about it online and found your thread.
I called the phone company's customer service and they said since I am a Mastercard holder they will return the whole ammount to my card, since they want to keep the good relashionship with the mastercard. Well that doesn;t make any sense and I assume there is something going on allready against that company since they returned that money right away.

By the way it was 4 short calls to Croatia from Germany (walking distance) and they charged me 260$.
On the side note Frankurt airport ppl were really nice and responded right away.