Different news....
It appears that Saban's brother is organising the event. I spoke to him and he says the carnival will definitely happen and it is on the 24th May. The Belediye will be doing some extra stuff for the 2 days following the 24th.
There is no program arranged yet and there certainly will not be anything like BoneyM but there will probably be some sort of group playing.
I'm probably not up in Hisaronu again until next weekend so if you need more details, go into the London Bar and ask Saban or his brother.
Hope that helps.