I'm on your time?!

Hate it when people seem to think that you are supposed to drop everything when they want something from you. My current situation is this: Got paid to program a register for a friend of a family member. The info was somehow mysteriously erased, so I had to program it again. Of course, this meant another payment. It sat at my place for a few days...guess it wasn't that important for business. Got a phone call the night it was picked up telling me I didn't so my job correctly. Also told that I needed to pay the individual that was going to being it back. My issue is that if it was that big of a screw up, it should have been brought back the same day not three to four days later. Then, you're the idiot paying your employees out of your own pocket to run errands for you. The day you choose to deliver it again is your day off. But, you can't deliver it yourself. You get a message that I'm on a schedule and need to fix the issue before a certain time. That time comes and goes, and no one shows up. Instead, I get a call a few hours later. Since the call is missed, and goes to voicemail, no message is left. When I call back, no one answers. As told by a relative, it's time to cut losses. Also, you need to quit thinking you are running things. I am not on your time. You do not run this. If it was so important to have things fixed so urgently, you would have made sure to deal with this issue accordingly.