What have you tried exactly?
Did you try the workarounds on the uesp/wikia wikis?
http://www.uesp.net/wiki/Skyrim:Repairing_the_Phial
http://elderscrolls.wikia.com/wiki/Repairing_the_Phial
* (360,PS3,PC) When you pick up the Briarheart, the quest will not update, and no option to turn them in will appear when talking to Quintus. Unknown cause (some author had 6 already but i was removed it with console it still won't work though). they cannot be dropped as they are now quest items. The way to remove any briar hearts from your inventory is to open console and remove the briar heart with player.removeitem 3ad61 1 code. The solution to complete quest is setstage MS12b 60 code. Make sure you do not have any Briarheart in your inventory when you take this quest.
* (360,PC) After drinking the potion, you can go to your misc. items and equip the vial thus duplicating it. The extra vials obtained in this manner do not refill though.
1) Well, let me detail how the quest broke in the first place. I had a briarheart in my inventory when I picked up the quest from Quintus which I did about 12 hours ago. When I picked up the briarheart nothing happened and it did not update the quest. When I returned to Quintus I couldn't turn the quest in since one of my objectives was incomplete. Now that that is out of the way.
2) My first attempt to fix was to go back and just try to reacquire the briarheart thinking that it was just a fluke. Again it didn't update the quest.
3) I tried to clear my inventory of the original briarheart before I picked up the quest briarheart but I couldn't remove it.
4) At that point I consulted the UESPwiki above like you suggested and input the following command (setstage MS12b 60). The command resulted in a prompt to "return to Quintus," and when I got there he had an arrow on his head but I could not turn in, or reacquire, the quest (I was a little unclear on whether or not I was backing the quest up or moving it forward). In any case it did not advance the quest.
5) I reloaded a save and removed the existing briarheart with (player.removeitem 3ad61 1) but, again, it didn't update when I picked up the new briarheart.
6) Another site suggested that I use the following commands to scale the quest back
a. (setstage MS12b 50)
b. (setstage MS12b 40)
c. (setstage MS12b 30)
d. (setstage MS12b 20)
None of them were recognized. I have yet to try going forward with (setstage MS12b 70) but I suspect that this will not work.
In short I have done everything that an end-user could be expected to do/know to resolve this problem to no avail so I moved on and continued playing the game without the awesome White Phial reward. Though everytime I use a Vigorous Healing Potion the glitch sticks in my craw.
TY for genuinely trying to be helpful though and not just telling me I ought to get over it like some retards.