If the insurer chose both repair shops, then you could claim that the insurer is acting in bad faith and deliberately selecting inferior mechanics to save money, and that this is causing you damage by delay. That would give you a lawsuit against the insurer, which would include both damages for the vehicle repair, but also punitive damages
to discourage future bad acts by the insurer.
If you chose the repair shops, then this is all just bad luck. The odds favor that the second repair ship will be able to fix the vehicle -- but, you have a claim against the first shop, not only for the poor workmanship, but also for the costs incident to the delay (e.g., car rental, lost wages, if you had to skip work to deal with the vehicle, depreciated value of the vehicle during the time that it was under repair, etc.). This is true, even if your insurer covers all of these expenses.
So, while you can't make the insurer total the car, you may have circumstances that will permit you to either hold the repair shop or the insurer liable for your inconvenience -- and if the insurer selected both shops, and they both cannot repair the car, then your damages would probably be sufficient to get the insurer to total the vehicle, because that would be cheaper than defending a lawsuit from you.
Those are the options. I realize that they are not exactly what you would prefer, but I can only suggest things that can actually be accomplished.
Please let me know if I can be of further assistance.