Staff is really unprofessional on evenings. If you're going to keep someone on hold for almost 10min and then when they call back thinking they were forgotten about, your response is "yep you have to hold," you need to find a new way to communicate with your customers. It's very simple to say "we're super busy at the moment, give me just a few more minutes," and then your customer doesn't feel completely disrespected and disregarded. Instead of blatantly showing the customer you don't care, maybe try to pretend a little harder.