XPS 15 (9550) after BIOS update and Win 10 update the TB dock has gone AWOL

A coincidence of two moments of carelessness and I have done the following: not first verified that my backup image is good (it isn't); approved a windows update (64-bit Win 10 Pro, version 1909); and accidentally triggered the Dell update which upgraded the BIOS to the latest version. I do not know if it is the BIOS or the sindows update which is responsible, but my Thunderbolt dock (which is essential for my ethernet, my phone backup, and my external monitor) no longer appears to work.
I have run SupportAssist to detect drivers and it claims that everything is up to date. I wanted to try uninstalling and reinstalling the thunderbolt drivers anyway but the driver updates error out - repair is disabled and uninstall/install report an error (errorcode 2 is reported in the logs, for what that's worth).
When I plug my phone into the USB port on the dock the laptop detects that a device has been attached, but it doesn't charge the phone and it can't transfer data.
I need this dock! Any ideas?
cheers, T