* Leaders Bayer win 2-0 at Augsburg
* Ibisevic hat-trick gives VfB Stuttgart 3-1 win (Adds details)
BERLIN, Dec 8 (Reuters) - The Bundesliga was plunged into a refereeing controversy after VfL Wolfsburg took advantage of a debatable first-half penalty, which also led to a red card for their opponents, to win 3-2 at Borussia Dortmund on Saturday.
Titleholders Dortmund were left fuming after a 36th-minute incident when defender Marcel Schmelzer was judged to have stopped Bas Dost's goalbound effort with his hand.
German media were unanimous in describing the decision as wrong after replays showed the leftback's knee blocked the shot following minimal and unintentional contact with his fist. Schmelzer was dismissed and Diego converted the penalty to make it 1-1.
Dost decided the match with a 73rd-minute breakaway goal and Dortmund coach Juergen Klopp appeared to refuse a handshake from opposite number Lorenz-Guenther Koestner at the end.
Vedad Ibisevic scored a hat-trick in VfB Stuttgart's 3-1 win over fading Schalke 04, where both teams had a player sent off, and leaders Bayern Munich won 2-0 at lowly Augsburg.
Fourth-placed Schalke's defeat extended their winless Bundesliga run to five matches, heaping the pressure on outspoken coach Huub Stevens, and allowed Stuttgart to pull level with them on points.
Ibisevic side-footed the hosts ahead after two minutes and put them back in front with a 38th-minute penalty after Ciprian Marica had levelled for Schalke.
He completed his hat-trick just after the hour before Stuttgart's Gotoku Sakai and Schalke's Jermaine Jones were given straight red cards for bad tackles within minutes of each other.
A Thomas Mueller penalty, harshly awarded for handball by Gibril Sankoh, and second-half goal from Franck Ribery left Bayern with 41 points from 16 games, 11 ahead of second-placed Bayer Leverkusen who visit Hanover 96 on Sunday.
Dortmund, unbeaten in their previous 12 games, went ahead after six minutes when a Marco Reus free kick evaded a pack of players in the penalty and went straight into the goal.
That brought only a muted cheer as the crowd joined the so-called 12:12 protests against new security measures proposed by the German league.
They stayed silent for the first 12 minutes and 12 seconds of the match before bursting into life by throwing a shower of yellow toilet rolls on the pitch.
Wolfsburg barely had a look in until the penalty incident when Schmelzer blocked Dost's goalbound shot with his knee and, although the ball may have brushed his fist as well, it was clearly unintentional.
Diego ignored the crescendo of booing from the wall of 25,000 fans in the standing-only Suedtribune in front of him and coolly converted the penalty.
Schmelzer's dismissal means he also faces a one-match suspension, part of what is known as the 'triple punishment'.
Amid general disbelief, Wolfsburg defender Naldo hooked in a free kick taken by fellow Brazilian Diego five minutes later to put Wolfsburg ahead.
Dortmund levelled from another penalty in the 61st minute, Jakub Blaszczykowski converting after Simon Kjaer clattered into Robert Lewandowski.
But the irrepressible Diego capped a superb performance by setting Dost on his way in the 73rd minute for the Dutchman to calmly poke the ball past Roman Weidenfeller. (Writing by Brian Homewood in Berne; Editing by Alison Wildey)