Oh dear - me again! I have tried the console commands to no avail. I can't increase my rank. I can bring Trebonius back but he is still mad at me and wants to fight no matter what I do (calm, charm). If I kill him or go to the arena and kill him, it still makes no difference to my rank - I am still a master wizard not an arch-mage. The weird thing is my rating with him is 100/100! I wouldn't mind, but I'm level 50 now and I really think I should be head of one guild at least! Plus it's driving me crazy that I can't sort this out - all because I challenged him too early in the game, sob.
I suppose I shall just have to let this issue go (after some major therapy).