(1) I have no connection to MSFT, but am just a customer like you. You could try the
Feedback Hub (ask Cortana). Be specific: Computer model, current Windows version & OS Build, problem description & the things tried. There also is...
https://support.microsoft.com/en-us/contactus/
Contact Microsoft
(2) I see that article says a clean install might work. You could shrink your C:partition by say 50 GB, & then install Win 10 v.1709 into the unallocated space. That will create a dual-boot situation. I did that once with v.1703 just to see whether this
Dell would take a clean install.
If unhappy, the dual boot is easily undone: a thing is done in MSConfig, the v.1709 partition deleted, & the v.1511 partition re-expanded.
If happy, the best thing is to repeat the clean install, this time wiping the entire HDD to unallocated space. That way, you get fit & proper partitions to suit just v.1709.