Man, that really sucks. Church leadership are very ungrateful sometimes. That is for example the reason I quit working as a sound technician. In secular events I always got a thank you and paid a small fee (last one not important to me), and christian (church) events people just approached me to complain.
Stay positive and remember that even though the leadership might have handled this the wrong way, the time you have invested in this has most likely blessed the church and God sees that. You will receive your reward in heaven. God never forgets!
Just out of curiosity... how did you get that gig? Do churches over there usually use bands that are not from the church? Because here you usually get an audition with the worship leader and a talk with the pastor.