My experience is that SLA "guarantees" don't actually guarantee anything.
Your provider might be really generous and rebate a whole month's fees if they have a really, really, really bad month (perhaps they achieved less than 95% uptime, which is a day and half of downtime). It might not even be that much.
How many of them will cover you for the business you lost and/or the reputational damage incurred while their service was down?