Hello!  Generally NBD support is contingent on parts availability so until they get the parts they can't fix it.  You do have an option for refurbished exchange after 3 attempts to repair the unit but it sounds like they are working on attempt 2.  If you want you can send a private message by clicking here, to Dell-Robert P. and he may be able to assist you. 
Bought Dell XPS13 in 2015. The screen died in January and Dell replaced the motherboard then. Screen died again 2+ weeks ago, and my case for replacement has been opened since. The Next Business Day repair is pending parts to arrive. What are my options? I am extremely unsatisfied with the support received, also not really trusting Dell to be able to resolve this issue, considering multiple people reporting same problem. (for example here) 
Waiting 2+ weeks for NBD repair - what are my options?