I used a bringt red henna on my brown hair, it usually comes out beautiful dark auburn this time it turned pin

I am getting married in 31 days, and i want to get this sh#t out of my hair before that. in the least damaging way possible. we are then going to Hawaii for a week for our honeymoon, and i am probably going to like have to hack off my pink soon to be sundamaged formerly nice, hair!!! help. ps what is the dilly o with the prell shampoo ? do i really have to go all the way to the dollar store, or wherever the heck they sell that crap, to buy that brand? and if so, why?