Most effective and longest lasting Salon Keratin Treatment

What’s the best Keratin Treatment? I know of bhave, Goldwell, CocoChoco, list goes on. I have long hair so I’ll be out of pocket around $350 which is fine if it works. My long, colour treated/foiled hair is particularly unruly in summer. I have a funky cowlick at the front of the part that is a bitch to tame. Who has had great success – meaning it lasts a good 4+ months? Not interested in straightening as to my understanding too many associated negatives – #1 is health of my hair. If you can recommend a salon in Melbourne, ideally near 3039 I’d be forever grateful. Thx!