I dunno about vinegar because its acidic I thought, and its alkalines that help to open the hair. But I am not really 'in the know' , 2 weeks ago I knew nothing of hair tests I've just been on the net researching.

You can just get a home dye and bleach and do it at home on an evening that's what I've been doing, but like everyone will tell you, hair tests go back 3 months so as far as THC goes you should be absolutely fine.

About the bleach, make sure its 40vol developer and powder bleach, Jerome Russel is a good brand here, not sure about over there but you can ask in the shop they will know. Then put a dye on back to the colour you are now and no one will know.

Good Luck