Persistent Mustard Algae

I have an 18 inch round above ground pool with vinyl lining. It was installed about 6 years ago.

I am beyond sanity. My pool water was gorgeous and then overnight I got this gold/brown stain all over pool. I have spent a fortune at my pool dealership, used green out, copper algaecide twice, both with zero results. Finally I took in a photo and they told me it was definitely mustard algae. I used Yellow Out per their instructions. No results. I waited a week and went back. They said my chlorine levels were high, to scrub pool, backwash and then apply which I did. Used a full large bottle of the yellow out, chlorbrite per the instructions, 3 pounds each shock 12 hours apart. no results.

I have now used Borax to raise my PH to 8.4. My alkalinity is 120. I am using clorox to shock the darned stuff. It is definitely lifting slowly, and I can see spots of black where it is dying. My chlorine levels are so high the text strip is almost black, and I am seeing very slow lifting of yellow/brown stains. But I would really like to be able to enjoy my pool. Can you help me PLEASE?!!!!!!