Edgars / RCS Interest

I had an Edgars account for many years with a 6 (six) month payment plan. Since they were taken over by RCS they suddenly changed my budged plan to 20 (twenty) months & keep on adding monthly interest to my account. I've send many e-mails to edg******* but without any success. What can I do to get them to change my budget plan back to 6 (six) months?