USA Student Visa Appointment in lagos

Hello,

Please i have sent a mail to US embassy to schedule an appointment as required because there are no available dates anymore on the online vfs website before i have to resume school in august. Its been 5 days and i am yet to get a response, does anyone have a contact i can call or an idea of the next steps to take?? does anyone have an idea of how long it normally takes them to respond and send you an appointment time??

Thanks