@ballet97 - the NACAC Statement of Principles of Good Practice, which almost all schools are part of, require schools to permit candidates to choose among offers of admission until May 1 - and the May 1 deadline “applies to any academic major or special program to which the candidate has been offered admission” (see excerpt below of the NACAC rules below). I believe the part of the rule stating that this “applies to any academic major or special program” was added within the past two years, so some theatre departments may not be aware of the rule and still believe that the May 1 deadline only applies to offers of admission to the university, not offers for specific majors (the old rule).
A good first step might be to contact the department and politely request an extension.
If you want to push the issue, you can contact the admissions office for the college, inform them of the situation, and ask them to intervene with the department. Admissions counselors should be happy to work out an issue like this.