Weird Letter From ESA

As well as still waiting to hear about my PIP renewal I'm in the SG of Income Related ESA and have been since 2013. I get an annual letter from them confirming payment amounts and that's it.

I received a DWP letter today, I immediately assumed it was about PIP, but it was about Your Claim For ESA. It just said we will pay you into the above account from September 20. Then some stuff about checking they have the right account and checking to see if the amount is correct. And that they will tell me if my allowance is going to change.

But crucially there is no information on how much they are paying me or why I've received this letter. I've reported no changes to the DWP. Its very odd. I wonder if its been generated in error or if its anything to do with the change over of Legacy benefits to UC. Any ideas please.

Several years ago, when talking to a DWP person on the phone, I asked why people got letters for no reason, which basically told you nothing new. She explained that if they go into your record either deliberately or accidentally, a letter is generated and posted to you unless they click on a specific box. So if they are busy or forget you get a letter for no reason. It would appear that this is still the case as people still report this on forums. It makes me wonder how much this costs over the course of a year.