Take a deep breath.  It's the holiday season, Dec 25th was an official bank holiday.  Things get delayed around this time of year.  Banking transactions can take a few days longer than anticipated during normal times.  I find all types of bank transfers and payments to be unreliable around xmas and new year.

Coinbase is a reputable company in the US, probably more reputable that the vast majority BTC companies out there, so you are very likely to get this sorted out either with them or your bank.