I have the same issue, it becomes easier as we go grey, thatís something to look forward too!!! My suggestion is ask the stylist to work on the natural base of your hair, use double the amount of ash than normal in the formula, reduce the developer quantity (this makes the formula thicker and so leaves a stronger deposit) and process for 10 mins longer than usual. This normally does work, make sure you are using a gentle professional colour safe shampoo and perhaps an ash conditioner at home as well as this way you can control unwanted warm tones as you like? ...More >
There are colour formulas especially for covering resistant grey hair and in my experience these ash formula are great at not just covering grey but adding the extra tonal deposit we need. They are commonly called 00 or NN.
I hope this helps