They can legally refuse an interpreter if there's an interpreter shortage. That's the sweet message we've been getting from the legal communities in St. Paul, San Diego, Atlanta, Indianapolis, Boston, and just about any other location that has a VRS call center established.
Looking into the case of University of Massachusetts, Boston, Case No. 01-90-2067 (OCR Region I 1991) (upholding university's decision not to provide interpreter based on shortage of interpreters in Boston area). The ADA law makes it clear that the interpreter shortages becomes a legal excuse for not getting interpreters.
Richard