As I indicated, lots of different things can cause sign-in or verification problems. Some of those things may be out of your control, but many may not be.
At any given time there are probably hundreds of users (out of millions) having a problem signing in. In many cases, there may be something the user could do differently to get around a particular problem.
The problem may have to do with a particular browser, browser setting, browser extension, browser cache file or browser cookie.
Perhaps the browsers you have tried already all have the same setting, history, extension or vulnerability.
Perhaps trying a completely different browser that you have never used before may allow you to get around the problem.
The problem may lie elsewhere, but trying another browser (even if you have already tried a couple) is an easy thing to do and takes less time than you spent waiting for a call back or on hold.
Perhaps your network or your firewall is blocking the Captcha verification or sign-in on ebay.ca, but not on ebay.com. Sometimes odd errors go away when network equipment is rebooted.
If you are sure you have tried absolutely everything then I guess you are stuck using your Android device to manage your selling account until eBay and Google change the way that verification works.
If that was happening to me, I would be frustrated as well. Then I would try a few different things. Maybe use your Android device to link a social media account to your eBay account, and then try signing in via the social media account from your computer using different browsers.
