Oh No! Please help

So to make a long story short. I was doing red for a cpl of months with the l'oréal hicolor high lights then decided I didn't want red anymore and I tried to strip my hair.. big nono. Ended up going to a salon who I thought was a friend and charged me $200 for the color I didn't want but I ate it. Well I decided yesterday I want red again but I want dark roots faded to bright red. I bought a tube of l'oréal chroma red garnet and 2 tubes of hicolor magenta. Last night I went to dye my roots and I read the chroma box and it says it cannot be mixed with other dyes. So I just did my roots and was going to finish with the magenta today. Well that doesn't look right. My roots are really dark and I shouldve done my whole head that color then added the magenta later. Question is can I fix it with dyeing my whole head 1 color. I have to go to work tomorrow so I need to go to sallys now and I don't ever ask them because the girls that work in the shop I go to never give me the right answer.. any input would be greatly appreciated. I'll add an image of what I'm going for. Thank you! *ott*