Per the DOS:
We are aware that applicants have been encountering problems reaching the Visa Call Center and that there have been some other points of confusion as we transition to the new Applicant Service Centers. Please rest assured that the Embassy, Consulates, and our contract partner, CSC, have been working hard to correct these problems. We appreciate your patience and apologize for any inconvenience caused by the transition.
Applicants who have been unable to contact the Visa Call Center are advised to continue trying as the Center has recently expanded its ability to handle these calls. Alternatively, applicants may wish to access the Visa Information Service at http://mexico.usvisa-info.com