This morning when I got up for work I had a text from my bank saying there had been a new deposit into my account, which I immediately checked as I wasn't suppose to be paid until Friday. Once I got logged in I noticed that 1) It was way way way more than I was expecting and 2) It was deposited by the IRS. Now this is what set things in motion. I had received my tax return in February, and it was the correct amount. The amount that was deposited into my account today was almost 6x more than I had been set to receive. As soon as the clock hit 7 am I called the IRS number to try and figure out what happened. This led to a half hour phone call in which they basically told me that they had nothing showing that they had deposited anything into my account(I did ask for that statement to be sent to me either by email or by mail which they refused) and I took down the reps name and badge number that I spoke with. Once I got off work I tried to do some digging but I haven't found anything regarding this happening. What should I do/Who should I reach out to to resolve this. The obvious this is I am not going to spend a dime of it(I called the bank and had them transfer it to my savings account as to avoid that), as much as I could use it. But I know the IRS is infamous for coming back several months later and demanding the money plus interest.

I am located in the US(if that wasn't obvious)

Edit: added location