Neat Customer Service Issues

I have an older iMac that was running Yosemite software. I was informed a couple of months ago that there was an available update. I allowed it to update. Since then, I lost a significant amount of my data dating back a few years, including my tax information and receipts for this tax year, due in a few days! I recently purchased a new iMac hoping it would solve the problem. Unfortunately, when I connected them to transfer data, NEAT did not sync properly. I attempted to contact NEAT but decided to update my old iMac to El Capitan first since the new one already had this version. However, it seems NEAT was not ready for this software update. I tried to apply a fix for El Capitan users on the new iMac without success. I have now purchased the cloud version in hopes of resolving this issue. I have spent several days on this and had two unsuccessful live chats in the past few days. I am feeling overwhelmed. Any assistance you could offer would be greatly appreciated.