i get another answer from amber coast:
they told me i received a slots only bonus when i created my account for signing up using a link from a affiliate website.
but i played this bonus down to 0,00 with slots.
after that i requested to unsubscribe from the bonus list and after that i deposited.
and there were no bonus rest in my account or in my balance.
i hope playtech contact amber coast soon and make everything clear.
but this is absolutely a warning to play in the amber coast.