After you file

Well if you are think that’s something I found my taxes and Suppose to get back $2000 and something dollars I only got back $624 Got a letter from IRS saying that they sent me out $702 which I think that it was a scam letter and on top of that I got a letter telling me about the refund from IRS and said that if I don’t think that the amount is right to contact them by May 26 and I still haven’t been able to get through to IRS. I found with TurboTax every year and this is my first time having this problem my bank statement said that my $624 was deposited into green dot bank and then later on I find out that it was deposited TPG. I don’t understand what’s going on but something just ain’t right. I received that amount of money in March and I haven’t been able to get in touch with anyone about anything . Can someone give me some type of feedback on this please! Who do I contact and what number can I get through to?