Poor customer service - Log delivery time of parts

Can you please help me to understand, how can it take more than 6 months to get parts for a car into the country? My Aunt has been waiting for parts for the past eight months for her CX5 car. My brother also had a CX5 and also waited for months for parts. It is really a pathetic service that someone is paying an installment monthly would have to wait such a long time to have their car fixed? How can this be resolved MAZDA SA?