Still waiting for Refund

Hello <br> <br> We travelled in British airways from Johannesburg to Livingstone on 4 April<br> <br> Our flight was derouted to Victoria instead of Livingstone <br> <br> We had to then travel in a bus from Victoria ,Zim to Livingstone , but we had to pay for visa on arrival<br> <br> We were been told by BA staff, we will refunded the visa cost , <br> <br> <br> we were 8 people , in that 6 were with SA passports, so there was no cost, but 2 people had Indian passport, and Zim Immigration charged us 100 usd per person <br> <br> So in total British Airways owes us 200 usd<br> <br> <br> Can anyone please assist <br> <br> <br> Thank you