The only shampoo for coloured hair which made a significant difference to my highlighted hair has been John Frieda's Sheer Blonde Go Blonder range.
I have just started using Kerastase Fibre Architect range instead and my hair has transitioned from lifeless, dull, fine with a tendency for frizz to glossy and full of volume. My hairstylist recommended that by focussing on the most pressing issue the colour would naturally look better. He has, however, suggested I use silver shampoo twice a week to keep the colour bright rather than brassy.
Sulfate free shampoos definately help colour last. I have resistant grey, it would fade out to a horrible orangey colour. Then I switched to sulfate free and it's brilliant, only have to worry about regrowth, not fading.
I use the redken Blonde Glam treatment conditioner to "lift" highlights. I use it once a week. Leave on for 3 to 5 mins and it removes any brassy fade from highlights. This, I've found, has made my highlights last longer so, gentle on my purse!
It's about £16 but, you don't need to use more than a 10p sized amount. However, NO MORE THAN ONCE WEEKLY or it'll make you lightest highlights lavender/blue.
Not noticed any difference to my highlights by using a particular shampoo. What has worked for me is washing my hair in lukewarm water and then rinsing it in cold water - the colour definitely seems to "seal" in more.
I can't find anything on line about conditioner so it's just my memory. The thing everyone remembers about the programme is all the hype about Boot's perfect and protect stuff. Have you noticed how young everyone looks since then.......
But I think she came up with 5 products worth keeping, SPF, the Boot's stuff, I think conditioner for coloured hair, can't remember what else.