Macdonald is ripping me off

On the 13th of April I bought food at Macdonald Springs Mall using their self service machines. I swiped twice and on both occasions it showed that the transaction was declined. I proceeded to pay cash for my meal. As I was still at the shop there was an sms notification that the transaction did go through on my side twice, I showed it to management and they just brushed it off and advised that the money will be credited back to my account.

It has been 2 months and still the money is not back in my account. I have been to Macdonald Springs Mall several times and given them my bank statement to prove all this but still the matter is unresolved. I find it very unfair that Macdonald would charge me 3 times for the same meal and then expect me to spend more money, more time and more energy just to get my money back. The service is truly appalling.