Refund

Hi i brought 2 return tickets from Durban to Johannesburg in March 2022 when i was about to go to Durban.. BA was grounded and instead refunding me my ticket was changed to a voucher so i cannot use that voucher to any flights and it will expire on Sept 2022 i tried to request my refund they only send me to www.ba.com no answer on their phone i dont know where to report them as they are liquidated forever.