Accidentally sent too much bitcoins.Company wont refund rest.What are my rights?

[babuB]

This has nothing to do with BTC, if I receive too much money from a company they will demand to get it returned. If I send too much money to a company they send it back to me. At least that's how things work in my country. A company refusing to do this is highly unprofessional. Your option may vary depending of where you live. If you gave money to a company that resides in a foreign country - bad for you, why did you even do that?
I would have the option to send a official request for money for which they have two weeks to react and can be escalated to a lawsuit which they know is gonna end with them paying everything, including my expenses.