I took a class at the YWCA, I finished the class but they won't give me the certificate? Advice?

There is an abuse course that is required by a lot of jobs I am looking to apply for. for 10yrs my main job, which paid very well, but I worked sometimes 10-15 hour days. I was looking to semi retire, and volunteer and work part time using my education in teaching, and counseling. but both the volunteer jobs and part time jobs requires this special 40 hour abuse class. So I found one. I spent 3 weeks 3 hours a day and I finished. I filled out paper work, But I was scheduled to have my 5th surgery a week after the class, and would not be able to volunteer for 3 weeks. When I was able to I called and said I was ready, and also asked when I could pick up my graduation certificate for the class. I called a dozen times and left messages. I went in the office and left 2 messages And to date I had not received a call or email. I basically been ignored. What can do legally?