I would recommend making another appointment for service. When you arrive and meet with the Genius politely explain your previous problems and request the manager so the three of you can discuss your options. Tell them that you are not satisfied with the repairs to date and that the latest effort really has you discouraged. Tell them that you would like to pursue the option of replacing the current machine with a new 2018 equivalent. If you are firm, but polite you have a decent chance of getting what you are asking for. If you do receive a replacement then it is up to you whether to continue with Apple or selling the replacement.
This is absolutely correct. But you can’t go in there and throw a fit.
Personal example:
My 2018 launch 15” MbP has been plagued with the BridgeOS crashes for about 4 months. I was finally in a position to send it in for repair. While it was in, I picked up a 2017 13” base model to use in the meantime, knowing I’d return it when mine came back. Apple had my machine for 3 weeks and essentially said they could not duplicate the problem, and sent it back, even though I specified that the issue only occurred when it was left to sleep with anything connected to the usb-c ports. Apple said specifically that they do not test for this.
After a couple of days of back and forth, the rep o had been speaking to at customer relations said that engineering wanted to look at the machine. I agreed, but stated that if engineering wanted to capture the machine that a replacement needed to be sent to me (I had returned the 13” as soon as mine returned). She told me that this was not possible, so I politely asked her if I needed to speak with someone in executive relations to make this happen. She immediately placed me on hold saying “as soon as you mention executive relations, I can no longer speak with you.”
A few minutes later a lady came on the phone and we chatted for a bit. I explained that Apple had the machine for 3 weeks, didn’t accomplish anything, and I felt that it was unacceptable to have to send the machine in for another repair the day after it arrived back in my possession. She agreed. The same day she escalated the case to engineering and said she would also call two Apple Stores here in Seattle to see if the team lead would go ahead and exchange it at retail to make the process quicker.
She called me the next morning telling me that she spoke with the lead at one of the stores and they agreed to replace it. When I return home on Thursday I will head over with my machine, box, etc, and there will be a brand new one waiting for me.
She told me they will process it as a repair, but instead of a repair they will replace it. Now, she did tell me that the warranty would continue as it is currently, which means I’ll have 6 months of the original warranty left. That part I’m not 100% clear on, but I fully expect she’s correct. Either way, I’m getting a new machine, and will put AppleCare on it.
tl:dr I sent the machine in for repair, and when Apple couldn’t fix it after 3 weeks, I politely moved my request up the chain, and they have agreed to replace it with a new one.
Don’t be a jerk, and they will work with you to receive the desired outcome.