I having same issue. Booked exam 2 months ago and couldn't find details of my appointment in regular account after account merge. Called test center and was redirected to call center, the voice over the phone was very very low and hardly to hear. Had to ask the call center staff repeat the question again and again. Eventually, online support confirmed appointment. Have to say PearsonVUE system is the worst online booking system I've ever used.
Yesterday, I sat the exam and couldn't get passed due my stupid time management. The exam wasn't hard as I thought before and I want to retake the exam ASAP. Tried more than 10 times today and keep getting the same error message as yours. I will call PearsonVUE tomorrow or maybe just send a message to vmware certification team instead.