Use the cloud they said. It will be fun they said.
Over what time range are you referring? Based on the 'millions' comment, I'm assuming you mean 'all time'. It's illogical to expect systems to perform flawlessly over a long period of time.
I'd also quantify the fact that it was only "unavailable" for a period. It's not like they lost my data.
What you are doing is a rhetorical trick called "moving the goalposts," in other words, "the marketing buzz was a big, fat lie; so let's instead try to spin it as if that promise had never happened."