Cannot hear phone calls unless using speaker

I just got my iPhone 6s back from a repair shop. I had dropped it in water. They dried it out, replaced the screen, battery and charging port. Seemed to work fine. When I got my first phone call, I realized I cannot hear the person unless I put the call on speaker. I also cannot hear a phone ringing when I make a call unless its on speaker. I put a screen protector on my phone as soon as I got it back and it does not appear to be blocking the speaker. I checked all the settings: it is not in 'do not disturb' mode; the ringer is on; the silent switch on the side is not switched on. Do I need to take the phone back to the repair shop or is there a setting I'm missing?