The Advertising Standards Authority has been asked to reopen an investigation into Microsoft's claims of 99.9 per cent uptime for its cloud services. The ASA was asked by a Microsoft customer to probe Microsoft's uptime claims after numerous outages of the Business Productivity Online Suite and Office 365 earlier this year.

The Reg is reporting that according to a letter from the ASA, Microsoft told the regulatory body that it had "omitted" the word "guarantee" in error and had amended the ads, making it clear that the uptime promise was linked to an appropriate service-level agreement (SLA) that justified the claims.

"Because Microsoft has already assured us that the advertising complained about has been amended, we consider there is little to be gained from continuing with a formal investigation," the ASA wrote.

In certain circumstances, advertisers or complainants can request a review of the ASA Council’s adjudication, including a Council decision not to investigate a complaint after its deliberation.

Both sides have 21 days to ask the Independent Reviewer of ASA Adjudications to review the case.  But they must be able to establish that a substantial flaw of process or adjudication is apparent, or show that additional relevant evidence is available.

The customer said that he was returning to ASA to ask it to revisit the complaint. "The ASA completely got the wrong end of the stick and thought I was complaining about the word 'guarantee'," he told El Reg.

"I have to pen a new complaint being specific about Microsoft not meeting their advertised SLA rather than stressing the 'guarantee' issue, which is important of itself, but only as a remedy," he added.

A search of the Advertising Standards Authority website reveals no information regarding the original complaint, nor the appeal.