poor car maintenance, poor customer service

We rented a car July 2015 from Europcar and had problems with a wheel bearing and no oil in the car. We exchanged it,
losing precious travel time, and had a flat tire in the midst of Barcelona on a Sat. rush hour. The car didn't have an adequate replacement tire and had to be towed. Europcar has kept our deposit with no explanation. The customer service was terrible, no one was helpful nor seemed to care.