Banging noise near alternator belt saxo vtr

[brian93]

Hi, hoping someone can help, for some time one my saxo vtr 2002, when accelerating I was getting a whining noise coming from the alternator or somewhere around there, sounded almost like a drill lol, this was happening for some time then it suddenly stopped 2 nights ago, now when the car is started even on tick over I'm getting a banging noise from that area and my revs are sometimes idling rough the worse the noise gets which sometimes very rare, but results in the engine cutting out engine management light has also came on twice lately for around 30 mins but then once the engines been turned of for approx an hour I turn it back on and the engine management light is no longer on, my main concern at the moment is this banging noise also regardless of if I've got the clutch held in or not its still making the noise, it does stop every now and then and sounds normal again but it doesn't last long, everything else is working as it should, can anyone tell me what this is and how I can resolve it, thanks