I don't know of any residential Internet service provider that provides access with any sort of SLA, uptime, speed, or otherwise.
If you want an SLA, you're going to have to pony up the bucks for commercial Internet service - and even then, it only covers access within the service provider's network, not bottlenecks in other nearby networks.
Yeah, well my jack off provider can't get me 3 megs (provisioned for 10) at 9 pm DIRECTLY TO THEIR SERVER 2 MILES FROM MY HOUSE. They have a speed test that runs directly to their server, not on any other network and I'm pulling 3 megs right now.
They have a bad node in my area and will only check it in the morning when everything is moving at optimum speeds. They refuse to examine at night.
And they are working on offering (that means charging for) 20-30 megs when they know they can't/won't provide 10 right now. I call that theft.