This is happening only against a couple of guys. They're donkeys but extremely aggressive which makes them a pain in the butt. This is happening within button/blinds dynamic.

Example 1: $1500 eff. I open 75s OTB to $40, V 3-bets to $160, I 4b to $300 he 5bets to $800, I fold, he shows 96s.

Example 2: $2000 eff. V opens button to $30, I make it $120 with AQo, he makes it $400, I fold, he shows 54s.

Where am I going wrong? What adjustments should I make given these guys proclivity to going nuts with light 4bs and 5bs?