Assalamualaikum.
When I experienced unfortunate that made me lose my money or must pay compensation, I always asked myself "What mistake that I've ever made, so Allah warn me?".
Since I was kid I've been taught that in every sustenance that I got, there is which the rights of needy people, and I must give their rights through sadaqah/charity. But, as ordinary human sometime I could be greedy. It made me forgot to give sadaqah, and spent my money only to buy something that I actually didn't need. In situation like this Allah may warn me through make me lose my money. This is what I believe.
Sister, probably what happened to you is a warning from Allah for the mistake you didn't realize. You lost your money when you wanted to buy chips and doritos. It's mean you were not hungry, but just wanted to snacking. But do you know?, there are many people who are really hungry but don't even have money to buy food. Did you ever remember them when you had money?.
I know that $3 mean for you. And if it mean for you, it must be mean for other people too. I am sure, the cafe employee is not rich. But he/she must responsible if some stuffs in the cafe lost through pay the lost stuff to the cafe owner. Do you know it?.
So sister, why you intend to do something that could make you being warned harder by Allah?.
My advice, you can complain to the vending machine owner, in good manner, not through anger. But if you still could not get your money back, let your money goes, and realize that it happen because Allah want it happen as a warning for you. In Shaa Allah, later Allah will give you more than what have lost.
