Forced to buy air ticket

I bought my traveling ticket to botswana online with a plan to come back with my car that got stuck there,but then upon trying to check in I was forced to buy a returning ticket at OR Thambo or loose my money. Then the sold me a nonrefundable ticket which is I came back with the car,but air botswana stole my money R2100 that I was forced to pay for a ticket I was not going to use anyway.