Tonight my fixed wireless has been exceptionally poor again. Even cartoons were stuttering and freezing. Download speeds measured out at about 0.5 (!) mbps, later gradually creeping up to a blazing 3 mbps. Inconsistent and unreliable are terms that come to mind.
Have you been in touch with Spark to see if they can improve it?
I'm actually with a small ISP but Vodafone supplies the connection. I think the issues are the same as with Spark. I have been through this in the past with my provider and there seems to be nothing that can be done until VF improves their infrastructure. Fortunately it is not always this bad, usually just when I want to watch something.