Thank you very much Ms. A for calling my attention.

Just between the two of us:

My daughter’s work requires her to use certain expressions a lot and she taught me that the correct expressions are “with regard to” and “as regards”. They were actually given a lecture on such things.

I wrote “… with regards to …” and that’s wrong.

In regard(s) to?

"The use of the plural regards in the phrases in regards to and with regards to is incorrect. Since each phrase shows its speaker regarding just one issue, the regard is singular: in regard to and with regard to.
[Examples:] I am calling in regard to your memo."
With regard to our meeting, I cannot attend." (Strumpf and Douglas, The Grammar Bible 220).

Or just ditch the use of ‘regards’ and use other words that will probably make your sentence better.

Here’s an easy guide on which is which.

Yup, I felt bad that I didn’t know about the difference but here are 12 words even smart people get wrong.