It is very hard to get ahold of the IRS this time of year. The IRS will send you a letter explaining the change in your refund amount. The letter can take 4 to 8 weeks to receive.
See the following for IRS contact information:
https://www.irs.gov/site-index-search?search=contact+irs&field_pup_historical_1=1&field_pup_historic...
