Double charged

On 27 March 2015 I bought Big Mac Meal X2 for R87 but when I was doing my online banking I noticed that i was debited twice. I immediately called the call center and was told to take the bank statement to the branch to claim which I did beginning of April but the manager on duty could not help me without the proof of payment as I had lost it. I kept going back to the branch to buy the same meal as it is my sons favourate, I tried again in August and this time a different person helped me and said she was surprised that I was not helped in April because one can go back and check the journal for the day in question but said she can try and help if I bring the bank statement. I have the bank statement but I cannot guarantee that I will get the same person on duty, the meal has gone up to R90 now - all I'm asking is for my money back I just cannot get myself to forget about it - please issue a voucher that can be spent at your outlet, I can settle for that