I would first reach out to the MT program and politely ask for an extension. If that fails, then get in touch with your admissions counselor or someone in the admissions department and ask for help. As referenced in previous posts, NACAC Guidelines stipulate a May 1 date for all offers of admission and scholarships including departmental admissions, such as MT programs. I think sometimes MT programs use these deadlines to see who is still interested in their offer, especially with the rise of “ghosting” among Millennials as a preferred form of rejection.