Oh no, you worded it correctly and have every right to EXPECT payment on the day it is due. All business expect to be paid or you can't take the item home from the store or the plumber will take you to court for payment and so on and so on. We have exactly the same right to be paid on the due date. And yes, I would have emailed or called yesterday if that was the due date. And I would add daily late fees. You can give them the benefit of the doubt that they made a mistake but it should NOT be repeated and they need to learn their lesson NOW.