Defamation and Theft

I am disgusted with the service and the policy in place at this business. My brother went to look for a part for his van and took his sample with. He did not know that there is a procedure to spray the sample before entering. There was no communication stating such anywhere. Even if there was who gives them the right to spray his sample part? Before leaving he was accused of theft of his own sample part and fined R400. What utter cheek to accuse my brother of being a thief when the actual thieves are this business! They still have his sample and they took R400 from him. Who are the REAL THIEVES here? I will be proceeding legally on this matter for defamation of character and for theft.