Sometimes Microsoft forget to charge you?

Problem

Its really helpful if you do cost reviews regularly.  Not only can it help catch cost creep, but also it can catch times when Microsoft mistakenly bills you incorrectly.  We have spotted a few times we have fixed things via a support ticket but recently we had an unusual one.

A team reached out to ask a question as their cost review identified Service Bus costs had increased significantly compared to the previous month.  These costs are normally quite static if you are using Service Bus Premium so they wanted to know if we had any thoughts on why this might happen.

Analysis

First off the cost review in Turbo360 makes it easy to identify the area where the costs have increased.

We then moved back a month and looked at last months cost review.  Last month the cost for Service Bus had dropped quite a bit.  

Two things were clear at this point:

1. The team hadnt done the cost review last month as they had been busy and they would have spotted this drop.  They had been too busy as often happens in many organizations

2. We need to also consider last month as well as the current month when doing this analysis.

We then looked at a graph showing the costs for Service Bus across a period of time grouped by Resource.  We could see that the cost was fairly static but there were no values for a number of days.

This seems not right and the first question is if Turbo360 had not collected a cost for those days.  To rule that out we checked Azure Cost Management but we can see the same behaviour displayed in Azure Cost Management.  You can see below no cost for these days.

The costs this month looked back to normal

Solution

The solution here is that the cost review was correct that the costs had increased.

The cause was a Microsoft billing error where they haven’t billed for these days.

The question here is if you want to raise a support ticket and ask Microsoft to troubleshoot this or take it as a win and worry about it later.