Loopyloo, I get a purple shampoo by L’Oreal from Amazon. About £20 for 1500ml. A bottle lasts almost 8/9 months. If you want to try it I can bring some along to our next meet-up next week.
Hello. You probably need a blue one to neutralise the yellow. Back in the day I had white blonde hair (ala Paula Yates) and it really did the trick of keeping it nice and bright (--until I bleached the beejeezus out of it and it all broke off)--