Sorry to hear that. It does sound like a FDR was performed. This is rare with an OTA but can happen, had you updated or been refusing an update that snuck in?
Other question is are/were you rooted? the reason is there could have been a rooted app that could cause this where as an unrooted system would not allow an app to get that far. Hopefully this is just a fluke, fortunately it does not seem to be a wide spread problem, of course this is of little, to no, consolation for the OP.