They HAVE to provide what is in the IEP. They even have to make up the hours missed so far. It's not your problem they don't have enough employees. I'd have some suggestions at the meeting, like you finding your own therapists they can pay for, or bringing someone in from a diferent school. I'm not sure the law, but I'm sure there has to be a solution.
My dd is supposed to be getting 3x/week of OT, 3x/week of ST, and 1x/week of PT. If the school is not following her IEP, can I do something about it? This school she's at only has 1 OT and my dd is simply not getting her services. I have a meeting coming up to discuss some issues, but how can I demand she get the therapies if they simply don't have the manpower?