Can you tell me how to get rid of extremely persistent acne?

It's not curable: It will eventually remit and otherwise you need to manage it. I was able to stop using Rx at age 50. If topical benzoyl peroxide has not cleared you in two weeks, get with your personal physician who can add prescription-strength Rx. If it's severe, Isotretinoin -- which isn't for the faint-hearted -- is very much worth considering.