I had those hyperpigmented areas too. Everytime I had a cystic pimple (I had otherwhise pretty clear skin, and those pimples always appeared on the same area...so I was left with clusters of red marks) it would leave a mark that didn´t fade for like months! Some didn´t go away at all.
I tried:
at-home microdermabrasion (temporary effect, lookin back it brought the least improvement)
at-home chemical peels (12.5% TCA, 40% glycolic acid, 60% Lactic Acid). Those were better, especially the TCA and the lactic acid which is supposed to be the best for hyperpigmentation
BUT
I was still frustrated by those things not giving me the kind of improvement I was looking for, with faster results. So I kinda prescribed myself Retin-A (my dad is a doctor, I had him order some for me without having a prescription from a dermatologist. And I only paid $4 for it with the discount we get!!!) and this has been giving me the best results in the fastest time!!!!
I do know my results are not typical in terms of my lack of side effects (I only get the tiniest bit of flaking on my chin, and my face hurts a bit if I use a not so soft powder brush on it. But otherwise my skin is baby soft and glowing), but my results are somewhat typical in terms of fading hyperpigmentation. I´ve only been using it for 2 1/2 wees, and my red marks are almost gone.
I do understand that some people´s post-acne hyperpigmentation responds well to OTC-products. Mine did too, but the improvement was barely noticeable, and it just wasn´t good enough for me cause I want perfect skin. Also, you have to try several products to find the one that might work for you.