Faded plum to rich brown?

Hi, I'm new here and would appreciate any help with my hair dilemma :)

My natural hair color is dark blonde. I don't know if it's a warm tone or not. The roots look ashy but when I had it natural the ends had a slight warm, coppery tone to it.

A year and a half ago I had my hair done violet at a salon and it looked great. I noticed that the level of fading became more intense as time went by and each coloring resulted in a less vibrant tone than the previous time it was freshly colored.

Eventually I couldn't afford the salon any more and I switched to box color (yes, I was incredibly nervous!). The first color I chose (Red Black) made my hair too copper so second time around I chose Plum. The plum was nice but within the week the copper started coming through again.

I have colored with the plum 3 times and that also fades to a copper (but not as orange as the Red Black-colored portion).

So my question is... how can I go to a rich chocolate brown? Will the color blend the natural ashy blond roots and the copper, plum red ends or is there going to be a stark contrast? (Brown roots with copper brown ends that once again fade to this stupid copper red??)

I appreciate any help because I'm quite nervous and wouldn't know which brown to even chose. I assume an ashy one to counteract the copper? But would that make my roots extra ashy or dull?