Matt Smith netted the 13th goal of his loan spell from Fulham to put the hosts in front in the 41st minute. The big striker got in between United’s two centre-backs to volley Luke Freema’sn cross from the left past goalkeeper Iain Turner from close range.
The Blades equalised in the 54th minute when Done forced the ball over the line in a scramble after substitute Jason Holt’s shot had been parried by City goalkeeper Frank Fielding.
And it was Done again on target from barely a yard out as Jamie Murphy supplied a low ball in from the left in the 77th minute.
Murphy completed the fightback with a solo breakaway goal five minutes later, cutting inside Derrick Williams to fire home after Luke Ayling had lost possession in midfield.
Smith’s goal was the only worthwhile effort by either side in a first half dominated by the defences. United lost Jose Baxter to injury after only 24 minutes and boss Nigel Clough sent on Holt as replacement.