Help me get rid of uneven skintone/farmers tan on arms!

I can't find anything online about this. It's usually just wearing fake tan to cover it up. I worked outside last summer and got an uneven tan on my arms at the shirt line from not wearing sunscreen and it hasn't gone away. I'm probably going on vacation in late may and I want to have an even base. I can't wear dresses or sleeveless shirts because it just looks bad :( I've been exfoliating with the korean mits on amazon which gets dead skin off great. But my skin not only has the uneven tan but scarring too. It's making me self conscious and I want to look hot dammit. What can I do to get rid of this?