For the last few months whenever I get my hair coloured at the hairdressers it is just not sticking to the grey hairs around the front of my hairline. My hairdresser is aware and has started using dye with "extra pigment" but it's still not sticking. I have held off washing it afterwards for as long as I can and have also not used conditioner when washing it prior to my appointment but to no avail. Starting to worry that I'll be completely grey for my 40th at this rate 
I just wondered if any of you knowledgable lot had any advice please?