Xbox 360 quest " deceiving the herd" trouble

[HackFireXx]

hi there skyrim folk . one day I just killed some random guy and an ash pile appeared. then a random quest called Deceiving the Herd popped up. did some research about it online.. found out that its a quest obtained from Feran in the vampires castle. went to him. nothin. the quest details are 'plant the letter of John Battle-Borns corpse'. confused. can anyone be of assistance at this hour? thanks everyone.

 

[MrDSL]

Wear the Dawnguard armor that he should have gave you..Go to said town and murder someone of importance in front of everyone wearing the armor.

plant letter on dead body and split.

 

[HackFireXx]

that's the thing though. I never went to him to start the quest. it just randomly popped up after I killed a battle-born. I went to Feran . the only option for him is his items to sell. no armor or nothing.