600USD upfront for one EX4 decompilation? Looks like fraud for me. If will never get the job done, they won't Provide you with a refund. This app is not really a decompiler, It can be just let you know to pay and send out the EX4 by way of e-mail. https://donovanfhhec.suomiblog.com/ex4-to-mq4-converter-no-further-a-mystery-46318535