I sense a lock quickly.
Nevertheless, there are no grounds for defamation, critical reception of a company's services is completely legal. Tsfx provides positive reviews of its services, and it is only fair that students who have paid good money for the lectures are able to provide the other side of their experience.
Oh and if you don't work for tsfx, or are lying about your claims of talking to Head Office, it would be very much advisable that you withdraw all your statements before things get more serious. On the flipside, if you DO work for tsfx, I am very sure that as a representative of the institution, referring to potential customers as "idiots" will not go down well.