Do we live in parallel dimensions???
I have the same issue, except mine might be a little harder (not bragging) in that I am at an independent and we dont have "HR" or corporate policy/violations to warrant any disciplinary action.
My tech is in her 50's. She could not pass the board exam if it meant her life. She was grandfathered in and I wish they never allowed techs to be grandfathered passed the process. Any competent tech should be able to easily pass the exam, especially techs with multiple years experience. She bullies my other techs, is very difficult to work with, and contributes to about 98% of the errors that occur in my pharmacy.
Before I arrived, she was the top dog. She worked the front counter, barked at customers, and did mostly adjudication. She was one of those empoyees that would try to do everything so she could take credit for it and the workflow was non-existent.
I complained to the owner and was told there would be nothing done about her and that she was "here to stay". So, if I couldn't get rid of her I was gonna let her know what was what. I took her off the front counter and now she has very little contact with customers. She longer gets to do order entry, as she lacks the basic math skills to appropriately calculate days supply or do dosing conversions/ calculations. She is now merely a "packager". It works, she has been knocked down a peg and has been much more pleasant to work with. You may want to give something like this a try.
If she doesn't want to listen, send her home. You shouldn't have to put up with that shizz.