Hi,
Have you even tried the in-place upgrade via ISO from the RP channel. This would take your system to 19043.867 just prior to the bug ridden update of .899 and then WU will update to 19043.928 or you could use the msu file from Microsoft Catalog.
This has worked for myself and many others. You might be waiting forever for MS to get this right. This has all been explained thoroughly in many threads already. You have to get your device off of 19043.899 first for WU to work.
Regards,