battery replacement

Hello, I was recently on vacation in Kauai, HI. My iphone 6 randomly died. I went to an AT&T store and they advised me to go to apple approved store to have the battery replaced since there was a battery replacement program for the Iphone 6. This store did say they would replace my battery, but my question is, are they allow to charge a labor fee of $45 on top of the apple charge of $30 for battery replacement? I took my phone to apple on the mainland and they told me that's not allowed to charge more than the apple fee since it's an apple replacement program. They also said the store should have ran a proper diagnostic to make sure it was the battery and not the board. Apple confirmed it was not the battery and it was the board. So this store not only overcharged me, but also didn't take proper steps to help. This store is apparently the apple store on Kauai. Is this store allowed to do this?