How do you manage blackheads on combination skin?

I have combination skin that is slightly oily only in the U-zone!

I've always been struggling with blackheads, but I'm not sure what method to try...

I tried using cleansing oil, but I didn't see much effect.

The BHA products didn't work at all, either.

It seems like my pores are getting wider. Please give me some advice on how to manage them!