Alright, I just sold all my stones to Mondan, and he hasn given me any money! Whats the deal?
After selling anything to a shopkeeper, to receive your change, you need to ask the respective shopkeeper for it. Typing: say to [shopkeeper] change, or “[shopkeeper] change, will have the shopkeeper offer your money to you, which you then need to accept: accept [shopkeeper]. And then you have all your hard-earned money in your hands! (Don’t forget to put it away).
