UPS Seasonal Driver Helper interview questions

Applied for the position, took a couple weeks and got an interview. There were 10 of us and the main guy told us briefly what to expect. Each of us had a one on one interview, which only lasted about 5 minutes, and got the job offer.

Interview was very easy. Basic questions. Training was very brief. However, UPS needs to learn to communicate between their HR departments. I explained to the person interviewing me that I was unable to work certain days for the next two weeks due to school, and she was fine with it. UPS called me anyway, and I was unable to pick up so the first day I called back after about 15 minutes and they didn't answer. The second day they called again so I called back after about 10 minutes and I explained to them I wouldn't be able to work until after 2pm because of school. The HR representative was irritated with me like it was my fault and they didn't call me the next week. I understand there's a large amount of employees but this company is incredibly unorganized.