Highly disappointed with tech support

My m15 lights stopped working properly and some other issues occurred, so I contacted tech support. The guy on the phone was very helpful, but the onsite tech did more damage to my laptop. So I had to send it in, my laptop has been gone for more than 10 days, they will not tell me what parts need to be  replaced, and what parts are on back order. Dell used to be known for having excellent customer service. Off topic my m15 can only take 16gb of ram clocked at 1600 :-(