I'm taking a test and have to guess the right answer to the question after the article. Article: Hundreds of people did not get their train tickets through the online train ticketing service after paying the money. The China Railway Customer Service Center said that it would try to solve the problem and return the money in 15 working days. The service center said changes would be made to the online booking system which limited each purchase which is finished in 30 minutes. Many people said that they failed to book tickets because of the time limit in purchase. People who paid without getting their tickets have formed groups on QQ. As many as 400 people had joined the QQ group by Thursday and the group continues to grow. The ticket buyers said their money had been returned through online banks but they didn't get confirmation from the online booking system. They are afraid that they will not be able to get refunds because they don't have the order number given to those who have succeeded in booking. People also said they were unable to inquire through the booking hotline 12306, because it is almost always busy. The China Railway Customer Service Center Website suggested that the online banks didn't return the payment information to the online booking system because of network problems. The online railway booking service was made by the Ministry of Railways on Dec. 21, in order that people can easily buy train tickets during the Spring Festival. Question: What happened to the train tickets buyers after paying the money? Options: A: They didn't join the QQ group. B: They didn't search the Internet. C: They didn't find the order number. D: They didn't get their tickets.
D