Re-Dying Hair After Balayage?

A couple of days ago I went to a salon to get a balayage. I have naturally dark brown hair, and have previously gotten a very natural/subtle balayage that grew out. It was the very first time I've ever put color in my hair. The hairstylist informed me that she was using Olaplex to lighten my hair. After about 4 hours, she finished my hair, however it was not how I wanted it at all.

It did not look remotely balayage, it just looked like she bleached my entire hair. I was in complete shock and I am freaking out. I asked her to fix it, and she told me to come back in four days. When I went back to get my hair fixed, all she did was apply toner to it. Upon finishing, the brassy/orange looking blonde was mostly gone. My hair did look darker, however it was a mixture of grayish blue and some blonde. She informed me that because it was a toner, it will fade back to the blonde I previously had after a couple of washes.

I left the salon completely unsatisfied and unhappy with my hair. At this point, I really would just like my hair back to its original dark brown, in order to avoid having to tone my hair so often/damage to my hair. Once my toner fades, will this be possible to accomplish in just one session? Or will my hair continue to fade to the blonde color? Please help!