John Frieda Sheer Blonde Colour Renew: Review

So, as you can probably tell by the bottle, I've been using this product for a while to try and solve my blonde woes. I like to give a product a good chance before reviewing it, so now the bottle is empty, I can give an informed opinion. John Frieda says: "Specially-formulated for colour-treated blondes, this tone correcting shampoo neutralises brassiness. The formula contains an optical brightener and lavender to extend the salon-fresh look of your blonde by neutralising brassiness. Contains UV filters to help protect your hair from sun damage. This product is ammonia and peroxide free."
As a bottle blonde, brassiness is an ongoing battle in between salon visits and I've been searching for the best toning shampoo, unfortunately, the search goes on. The bottle advises to apply as normal and leave on for a few minutes before rinsing. I followed these instructions and followed up with the toning conditioner from the same range but saw little to no improvement using it as a every other day shampoo. However, when I have a bit of time to kill in my house, I'll leave it on for a lot longer (up to a few hours) and this is when I see the product working. I feel that this product and range is perhaps more suited to medium blondes, as the brassiness is a lot less brash and perhaps easier to counteract. I will give the product a thumbs up for no ammonia or peroxide, still, I'm not taken by it at all and will continue on my quest to find the best! Suggestions welcome!