Radisson offers promotions for shipboard credit on various cruises. Mostly South America and the World cruise but others as well from time to time. Sometimes there can be an on board credit as a compensation for a problem. When these are offered everyone gets the credit.
Then some agencies are associated with Virtuoso and Giants. These consortiums (Virtuoso and Giants Select) often offer a $100 shipboard credit either per person or per cabin on "select" voyages, those that the consortium is sponsoring as special voyages.
So if you get a combination of these it can add up for you which is what it sounds like in this case.
Anyway as you say ---- here you go to the spa.