Computer service business

Ajit Bhosle (Student) (22 Points)

14 June 2021  
I have a shop from where I provide repairing of computers, spelling of computer parts such as keyboard mouses hard disk etc etc...and I also provide sale and installation of CCTV 's...
so under GST in which category I come? sales of goods or services?
and shld I apply HSN or SAC code in invoice??