Hi Freddy, thanks for the answer.
The drivers you pointed me to, are the ones i alredy installed (15.7.0.3). Looks like 15.8.0 refers to the version of Intel's additional software.
I was able to fix only the bluetooth headset issue by buying a Dual Band router (and connecting to the 5Ghz network), but i'm still encountering stability and other issues (unrelated to bluetooth).
In particular i noticed that after encoutering some issues, Intel's "Manual Diagnostics Tool" reports the Intel's wireless drivers as missing; i can fix that by reinstalling Intel's drivers and rebooting but it's annoying.
I tried again contacting DELL, but since my laptop shipped with Windows 7, they are giving me a hard time proving this is a hardware fault.