British Airways terrible service and ethics

Arrived on time for check in for my 10:30am British airways flight from JHB to Dur only to be told they have over booked the flight ,a flight which I had booked and paid for 3 months in advance.They then left me standing around with 5 other angry passengers for over 45 mins without letting us know what they were gonna do about it.When the manager finally arrived he was arrogant and rude and pretty much told us there’s nothing he can do and we can be put on the 3pm flight or ask for a refund.I think British Airways are a group of cheats that over book just to make an extra profit and don’t give a flying **** about there customers.truly disgusted