Maran, in Siman 307, deals with utilizing a non-Jew to prevent a major financial loss, Heaven Forbid. For example, a fire or flood threatening valuable merchandise. Clearly, it is prohibited to instruct him to perform a Torah violation of Shabbat, such as moving merchandise out of harm's way from the public domain into the private domain or extinguishing a fire. That would constitute only one "Shvut"-Rabbinic prohibition.
However, the Hachamim permitted utilizing a non-Jew to perform a Melacha to avoid the great loss under certain conditions. They reasoned that since "Adam Bahul Al Mamono"-A person panics when his property is threatened, if he is not allowed to use a non-Jew, he is likely to panic and "take the law into his own hands" and violate the Shabbat by putting out the fire by himself. Therefore, they made a dispensation to allow either calling a non-Jew to the scene without giving him any instruction, assuming he will know by himself what to do; or to announce "Whoever puts out this fire will not lose"-without specifying any person. This is permissible even if he says, "will not lose out monetarily," in which it is clear that he intends give compensation. This dispensation thus enables the non-Jew to perform a Torah prohibition of putting out the fire.
If the Melacha to be performed by the non-Jew is only Rabbinic, the Mishna Berura (Rav Yisrael Meir Kagan of Radin, 1839-1933) permits directly instructing the non-Jew. He likens this case to the case of Shvut D'shvut (double Rabbinic prohibition) for a Misva. According to him, the Halachot of major financial loss are comparable to a Misva. However, Hacham David cites Poskim who disagree and rule that cases of financial loss are governed by different rules than Misva. It is never permitted to instruct a non-Jew directly-to perform a Rabbinic or Torah violation. The Hachamim were concerned that a person will panic and violate Shabbat himself, and therefore they created stricter rules. This is a rare case in which Hacham David is stricter than the Mishna Berura.
In a case of major financial loss, it is prohibited to directly instruct a non-Jew to perform any Melacha (Rabbinic or Torah) to avoid the loss. However, it is permitted to indirectly engage his help by either calling him to the scene without any word of instruction or by announcing "Whoever helps will not lose out."