Humming sound during accelerat and whining noise while removing leg from accelerater

Humming sound during accelerat and whining noise while removing leg from accelerater
I own Chevy Cruze 2013 Automatic Korean with GCC Spec 1.4 engine already crossed 130k owned it before 2 months. Now i am hearing humming noise while accelerating and bed whining Noise while removing leg from accelerator. I think the Transmission not shifting automatically. i shown to the mechanic but he threatened me its very big will cost too much. i have a doubt whether its a problem with transmission Fluid or any other issue. the vehicles picks up rpm and speed very late also.Please advice me what to do with this.