After you file

I filed my taxes on 1/26/19. It was accepted immediately by the IRS, then one week later it said there is a delay with my refund. I called the IRS with the code provided and I was told they have until 4/15/19 to complete a review of my taxes. They didn't need anything from me. On 3/13/19 I received a letter stating they will need an additional 60 days to complete the review, again they don't need anything from me. So I am looking at the end of May or first week of June before I receive my refund with no explanation for the delay. All of my information has been the same for the past 5 years.