The celebration party for the departure of Roland from The Valley did not go well with Sheffield Wednesday winning 3-1, although Charlton stay 17th in the table.
With only five players to choose from on the bench after Ben Purrington was forced to pull out, some Charlton players were also struck down by vomiting and diarrhoea. And the Addicks' injury crisis worsened further when they had to keep Oztumer on the pitch after he suffered what looked like a hamstring strain.
Following a neat exchange of passes with Morgan Fox, Bannan curled over a superbly weighted in-swinging left-foot cross from close to the left flank and Fletcher nipped in just ahead of his marker Naby Sarr to steer home a deft header just inside Dillon Phillips' left upright.
But, just nine minutes later, the Addicks levelled out of the blue. Recalled teenager Alfie Doughty surged down the left flank to find Bonne with a low cross and the striker's half-hit left-foot shot took a deflection off Tom Lees to wrong-foot Owls keeper Cameron Dawson for his sixth goal in 11 games.
It took until 10 minutes from time for the Owls to go back in front from the spot. Murphy went down as he knocked the ball past the labouring Oztumer, the penalty was awarded and Fletcher stroked his eighth goal of the season into the bottom left-hand corner.Bannan then proved the architect again when he picked out Nuhiu to wrap up the scoring with the simplest of headers deep into added time.
Lee Bowyer said: 'It was a tough day. We've got enough injuries, but then to chuck in a few illnesses as well doesn't help. It was a bit of everything. Sickness, diarrhoea, not good.'
'Ben Purrington was down to start, but he was ill just before we got on the coach, so we had to send him home. Then once we got here and put the team sheet in, Albie Morgan was being sick just before the game. We couldn't do anything about that. We just had to see how he went. Then again at half-time he was sick. That's why we took him off. He couldn't move in the end.'
Bowyer said he had spoken to the new owners and 'They have said that there is money to spend in January and that me and the staff are going to get proper contracts.'