I Am On Vasotec, Prazosin, Metoprolol And Lipitor....have Been On

I am on Vasotec, prazosin, Metoprolol and Lipitor....have been on all 4 drugs for over 10 years...I suffer from high BP, MVP and Ventricular arrhythmia....also fast heart rate....these drugs have kept me in really good shape. However, My cardiologist retired and my primary tried to renew my prescriptions with Express Scripts. They are saying that the Metoprolol will cause a problem with my other drugs and have convinced him to cancel. These drugs have worked! Why would Express Scripts say there is a problem?