The fact that upgrades require diamonds and diamonds are so hard to come by sucks. Not upgrading makes it hard to win higher levels. Also the automated machines for each restaurant are only on offer for a few days, and if you don't have enough diamonds, there's no option to get the machine at a later time. At least give us time to accumulate the diamonds for the equipment without putting a time limit if you're going to make the diamonds impossible to get a good amount of.