Please help: Glitch in Escape from Castrum Centri Quest

I have accidently thrown away the Mended Imperial Pot Helm and Mended Imperial Short Robe from the Dressed for Conqest quest, now I am on the Escape from Castrum Centri Quest and unable to complete it because of the Imperial Helm, I've tried to locate it from the Calamity Salvager, talk to Glaumunt for a replacement set and searched my inventory to no avail.
Can anyone help me? I cannot progress through the rest of the Main Storyline quest without this!