
They did call for help, read the earlier chapters again, It showed Minjoo's Dad's were holding him at the location he was kidnapped, they called them to go there. And usually when people kidnap or commit crimes, they cover their face. That's why they didn't recognise Professor Cha, he wore a mask when he kidnapped Winjoo.

Blondie was a kid, it would have been obvious it was him who did it. Minjoo was kidbapped by an adult not a child. You can tell the diffenrece between a kid's build and an adult's build. Also, it doesn't make sense he'd kidnap Minjoo when he had access to Minjoo all the time, Minjoo even said his Dad's practically raised Blondie. They were friends and were practically joined
by the hip, why kidnap a friend you're ALWAYS with?

Read Chapter 24, the Uke was kidnapped and held captive at the house of a national assembly candidate, which was Mr Cha's Dad, they even show Mr Cha's Dad was there in the season 2 premier chapter. Why would Seme, as a middle school child, kidnap another middle school child and hide him at Mr Cha's Dad's House? Also, only an adult would be able to subdude a child. Mr Cha knew his son did it but covered up by saying it was political and a rival was trying to frame him for it, hence why Uke was found in his home. Seme was a witness to the kidnapping who called for help and stayed with the injured Uke untill the police and Dads showed up.
Professor Cha is the person who kidnapped Woojin and his father covered it up by acting as if he was helping Woojin. Also, what an idiot Alpha, why would you give your BEST friend and crush black market pills. What if it kills him. I'm so mad!!!! If anyone i know did that to me, I'd cut them off. He clearly doesn't care for Woojin's health or safety.