You're using the wrong color levels and in the wrong tones!!! This is one of the reasons why I dislike box dyes. That Garnier LB1 is a level 10 cool (ash) tone blonde and using that on grey hair will only tone it resulting in the platinum blonde shade you currently have. As for the D&L Golden Bronze, that's a level 7 golden medium blonde it's not going to do much of aything for grey coverage. In fact, it'll just give a gold highlight. You'll need a darker color with a neutral tone for grey coverage.
Before I recommend anything. Do you have a photo of what you mean by dark blonde? Also is your hair relaxed, permed, natural? How much grey do you have? Also do you have any beauty supply stores or Sally's in you area?