Tax credits phone interview

[anotherdisaster]

Hi All, I got a letter from the Tax credits the other day saying they are reviewing my tax credits and this will be in a form of a telephone interview. It specifically asks me to have details of childcare payments ready for the interview. I was rather alarmed by this as I've never had this before.
I have checked my online account and the average weekly amount I pay for childcare is slightly more than it should be. I worked out I've paid on average around £16 per week, but it says £20. I had tried to change this when it was renewed but I get an error 'unless the payments change by more than £10 per week, this will not affect your payments'.
Has anyone else had this? Is this just a random spot check?

Random spot check.
I had it a couple of years ago.
You pay out more than you claim so it's nothing to worry about.

I've had this recently. I hadn't changed my childcare costs for a couple of years by more than £10. In fact I pay a little more than was originally on my claim.
I just confirmed the breakfast club and after school club costs and they were fine.