False advertising from BA

Booked a flight three months in advance to fly back from Durban to Johannesburg. As I arrived in Durban, I received a mail to say the flight, an afternoon flight was cancelled. Tried calling, and the call center said that all flights later was full. I immediately booked on another airline. The next morning i received an e-mail from BA to say that i now was on a flight 4 hours later. Left me stuck with an extra ticket. Very poor, cannot trust airlines anymore. A form of false advertising