I have come to value vendor communication/transparency more and more. Here’s a recent snipped from USAA auto:
We're writing to inform you that an error was made when calculating the premium for your auto insurance policy. This occurred between October 2017 and August 2020 and was caused by a rating error related to your uninsured motorist property damage coverage. The problem has been corrected and **a refund, with interest, has been issued**. > > (**emphasis** added)
I haven’t logged in to see if we’re talking about a $2 refund or a $100 one, but this is the kind of thing USAA admits and handles well. You may remember they issued credits for several months when people started driving less during early Covid lockdowns.
Another example of good comms is how Amazon handles TOS changes. They link you to a “What’s changed” page that explains in plain English how the terms have changed.