Deposit for online bookings will be lost on cancellation

They are friendly - but you can never cancel a booking. I tried cancellation online. There is a cancellation button on the booking site. The response says that there is not enough time for the transaction. I phoned in several times and was assured about the cancellation being done. But the reminders for collection came through. I went into the office in person at the King Shaka airport for which I had booked and later cancelled the rental in person. I was assured that it was done and my deposit would be returned - again no such thing happened. I lost the depopsit for a cancelled booking on 16 May and again on 22 June.