defamation business

I'm very upset and repulsed by the African Bank consultants in germiston Golden walk mall, the consultants are bad mouthing and telling lies and giving out improper information about my company's services. The ladies by the names of Lattia and Lenna told the client, false information about our services, and that is unacceptable and more so unprofessional of them to give and when asked to speak to the manager a lady called Busi said she's the manager but had no identification stating she's the manager could not reprimand her stuff and tell them to stop spreading rumors and lies about other companies as that is defamation and could bring harm to the other business.