Richards Bay Broadwalk staff needs training

For the whole year I have been saving money into a voucher card to enjoy with my family in December. I asked the cashiers at the till in Richards Bay Broadwalk to split the voucher by purchasing another voucher using the original voucher i have been toping up through out the year, she called her supervisor who told me its impossible, i begged her and told her its just common sense she did budge. I have phoned head office and they are telling me I can be able to purchase a voucher using another voucher/rewards card. Please teach your people in the stores and provide them with product training because customers end up being frastrated. Head office said they will phone Richards Bay branch to help me so I will go back and see if the staff will be willing to help me this time around.