Suddenly huge fan noise and Alert on Service Tag not programmed

Was happily working away on my XPS 15 9500 laptop, and decided i would quickly restart it due to the fact I had so many windows open and memory usage was over 50%.
As I stepped away i noted it was doing an update.
On return I now have a huge amount of noise from the fan: checked my HWinfo & system task manager - temperatures are fine GPU 55, CPU 60, xps 15 9500, CPU maxing at 80% with browsers but no reason for fan noise.
Eventually rebooted laptop into BIOS after numerous attempts - so fast. During this I was warned I had no service tag - it shows in windows, and is read on Dells website?
Tried adding Tag, unsuccessfully it appears as fan is still excessive. there was no 64 service code dont know if i need that?
Tried support but the bot kept asking had I dropped it and refused to go further because i said NO, despite having explained issue. Unfortunately I am out of warranty - any ideas how I get those responsible for causing this issue via their update to do something about it.

Its a bit like the issue with the battery sending laptop to sleep - despite discussions with Dell it was my problem - even under warranty. During discussions they never once said change settings for Critical battery action to "do nothing" as a temporary fix. Now I regularly see a popup warning me about the battery but it does not stop me working any more .
However this fan noise has made laptop unusable no way I can concentrate with it.
I woild be very glad to hear from anyone with any ideas on how to resolve this problem, or on how to contact Dell to get a solution.