Business ProfileforMac of All Trades

I have ordered at least 5 iMacs from Mac of All Trades over the past 14 years. I used Adobe programs so the computers get a very hard workout. I've always ordered the iMac that is graded as "Excellent" and they have been just that.But last week I ordered a refurbished 2019 iMac that they graded as in "Excellent" condition, meaning "Minimal wear based on the age of the product." Instead the iMac i received is actually in "Fair" condition, meaning "Heavy signs of usage. Machine may have technical limitations. Read product listing for specifics." I have another iMac I bought from them that when started, takes less than one minute to open with all icons and dock visible. And less than a minute to open one of the Adobe programs I use. This iMac takes 13 minutes from start to opening a program and then the screen freezes. When clicking or typing the Spinning Wait Cursor constantly pops up and can take several minutes to disappear but sometimes doesn't and the computer freezes. I have to shut it down manually and reboot it. These problems are taking at least 1.5 - 2 hours out of my billable hours EVERY DAY. That's 30+ hours a month I can't bill my clients. They did NOT refurbish this machine. It arrived with the Mojave Os from 2019 and I followed the instructions to upgrade the software through two newer Os versions. But this didn't solve the problem. I have tried contacting them through their "Customer Service" chat box, email and tried calling both phone numbers. The options on both phone numbers don't have an option to speak to a tech person about a dysfunctional computer. I uploaded images to their "Customer Support" chat window showing time/date stamped images of starting the computer right through to finally opening a program. My order number, receipt and screenshot showing the product listed as in "Excellent" condition and 26 hours later, no response. The return window is only 14 days. I suspect they are going to try to stall me.