Tell them you want in written "This only cause by VLC and that why they decided not to replace your speaker.". And also asked them are you sure your engineer's can proof in court. Why this is customer fault who put this speaker in this system in first place and what about other Dell laptops why not they encounter with this type of problem. So, Dell is responsible for putting this piece of junk in your system not you. Believe Dell engineer are $hit they only blame their problem to other.
I also faced other issue in my 15z, so simply ****ked them badly asking explanation and they are out of option . However I'm very old customer of Dell because of there service they provide similar or almost similar kind of service in every country, the problem is all country service support is deal by India and that the biggest problem.