Service at Mazda East Rand is terrible

Ordered a part from Mazda East Rand. Person at parts department confirmed the part will be available the next morning as i paid cash for the part. Went to mazda following morning to collect part, as the person said i don't need to phone the part will be there. Arrived early morning at Mazda East Rand and the part was not there, he promised to phone me back with more info and i did not receive any calls as promised. Phoned him following day and he claimed the part is still not there seems like someone else took the part. I have already paid cash for this part and i have a broken car. He would phone me back at 9:00 with feedback. Its been three hours later and i have received no call from Mazda east rand parts department. How do Mazda East Rand Parts department give away a ordered and paid part to someone else? and why don't they contact you with feedback on how the progress of this issue is going? And why is the person in charge of Mazda East Rand not available to assist with this problem?