Poor customer service

I booked flights for 6 students to Beijing return. STA advertises free date change for students, but does Not inform about t&cs. It took 3 months of calls and emails to get tickets booked and he still misspells a name. On the return trip, we couldn't change dates so the students missed an exam. When they got to check in, two were allowed to board, the other four were told that their tickets from Dubai to Johannesburg were not confirmed. Even though we contacted STA immediately, they couldn't do anything about it. Manager Robert Stables then took over and said we would have to pay R5000 per student to get onto the next flight. After hours of haggling over the phone, STA blamed Emirates and vice versa. When boarding opened for the next flight, after 12 hrs, Emirates allowed boarding for R200 per student. It's nearly 6 months since and they still playing the blame game and seem to have forgotten about the incident. I still believe that STA, as booking agent is totally responsible. I have 8 students traveling to Beijing twice a year, but will Never use them again