Hair Lightening Advice

Hello.

I have quite a lot of body hair (legs, arms, hand, feet) etc which I don’t mind when it is lighter coloured and sun kissed, but I hate it when it isn’t. So I bought some hair dye to use, and encountered some issues that I would like some advice about if any of you would be so kind.

I bought a blonde permanent hair dye (Garnier Nutrisse Ultra Blonde) and applied it to the hair on my hands and feet (toes and knuckles). Weird I know, but I thought it was a good test to make sure it worked. Anyway, at first it worked perfect and looked natural, less noticeable and sun-kissed, just like I wanted. But then after a couple of days, it started to fade a bit generally - but the main issue was that it faded from the top of the hair all the way to the bottom. So for a while, the hairs were part blonde, and part dark brown (the original, natural colour) - with a very distinct point at which the colour changed, so much so that it looked like it was two different coloured haired that had somehow connected. There was an exact, straight division of colour.

I know the dye was intended for head hair, and I do shower twice a day, but surely a permanent hair dye that worked fine at first shouldn’t fade so quickly, and even if it did it seemed odd how it worked it’s way down in such a regular fashion? Is that particular dye just rubbish or have I likely made a rookie mistake? Or maybe it just won’t happen. Just want some clarification.

Thanks for your time, and sorry it if seems like a stupid or weird question.