Hey Michal,
Glad to hear from you again.
I don’t think they can collect this money from you. Don’t worry about this. Just don’t answer the phone ever again. I would suggest you change the number as well.
I don’t think you can do a lot from the MetaTrader because even if you close the trades, they will open new ones. Anyway, on the right side where you see the losses, there is the x box. Try closing from there.
As I said, ignore all and continue your life. Forget about it.
Cheers.