this is my speciality in hairdressing!
before you think about toners, GO BACK TO THE SALON and get it spot bleached, this only takes 5 minutes im sure your salon has time to do this.
what sort of brand does your salon work with? loreal? wella? if loreal, use p02 luocolor milkshake NOT p01 as i find this tends to bring down the depth around half to a whole shade, po2 is used is the hair has a yellow underbase as it has a violet underbase rather than a pearl one. if your salon works with wella, then i would do a very strong toner which will clean out the blonde as well, (i really do recommend using wella rather than loreal for bleach platinum blonde) this colour really does achieve the most beautiful blonde, use 10/16 koleston perfect with pastel,
you will get a beautiful ash creamy blonde with absolutly no brassiness, but make sure your salon bleach spots first! bleach spotting only takes literally 5 minutes, this happens when the stylist has not allowed enough development time.
and ive tried out many silver shampoos over the years on clients, and be far the best one is lanza silver shampoo, it carries natural viola flower and is INCREDIBLY strong, i thought loreal professionel silver was strong but this thing has a mind of its own, i cant tell you over a computer if your hair is porous or not, but if it is use a DOT of this shampoo, and then mix the rest with another shampoo called silka quick silver, the ratio should be around lanza 1:4 silka, finish with silka quick silver conditioner. if your hair is not porous you can use half and half lanza and silka shampoo.