I can think of 3 companies that I have "left". Left can mean a couple of things:
1) A scheduler was blasting my email, I mean REALLY blasting, making it difficult for me to take time to look at other postings. So I blocked the SCHEDULER - I didn't do any work for them.
2) A scheduler/owner responded to a question I asked with a rude response where cursed and attacked me. Seeing as how he owned the company, I left /deactivated from the company. I don't want to work for a company whose leader is not only a bully, but so crude also, no matter the job. I am fortunate enough to not depend on the income from mystery shopping for a living.
3) There was an MSC who signed me up for jobs when I asked a question. The first time, it was no problem to complete the job. I let the MSC know that I did not appreciate it and not to do it again. I told them this time I was doing the job to help them out, because I know we all need a little help sometimes. The second time they did it by asking me to do the shop. When I responded no, they simply assigned it to me for a different date. I responded by telling them I would not do the shop and to stop scheduling me without my request. I also escalated, to no avail. The third time they sent out the job request, I didn't even respond. Then the scheduler began blasting my email, so I did the next best thing. I put an auto-reply to anything that comes from the scheduler. I have semi-left the MSC. I can always go back in when times are slow to look at what they have. But I no longer receive notices from the MSC.
When you learn, teach, when you get, give. Maya Angelou