Unsigned drivers maybe.

Hi,
My Windows 10 1803, updated when necessary since the original version, has been running normally.
Recently, I'm not sure when, my USB 3 stopped working completely. It's a very long story of what I have tried to rectify this but here goes on a shorter version.
In device manager located the problem being that the USB xHCI Compliant Host Controller could not be started. "This device cannot start. (Code 10)" message.
Tried 'Update Driver' - Windows searched and returned "Windows has determined that the best driver for this device is already installed". Driver supplied by MS.
I went to the Gigabyte people and explained the problem over a couple of visits and established that the bios and chipsets are all correct etc and up to date. One oddity is that VIA in their support pages say that for Windows 10 no additional drivers are needed, but have four updated drivers for the USB controller for download.
I tried installing all available VIA usb drivers but device manager still insists that theirs is best!
Presumably these VIA drivers are unsigned so Windows wont use them - is it possible to force Windows to install an unsigned driver?
Microsoft help and support is almost unusable in deperation but I have booked a phone call for next week!

Any suggestions?
Roger