They may have been unsubstantiated but would explain the...

They may have been unsubstantiated but would explain the increased volumes post SPP announcement. The fact that there was no notice means little as you are unlikely to see a notice until instos finished buying .
Also the retail holders would hardly pile in at 9c+ when they could get some at 7.8c so its unlikely that it was the retail holders that increased the traded volume 10 fold. But you did get one thing right, the retail holders are piling in and having the SPP amount increased again suggests they are prepared to support the company and know a good stock when they see one.