MrD service is wack!

Yesterday I ordered via App and selected collect option.... The App gave me error messages as I was about to finish the order twice... I resorted at driving and got the food via drive through only to realise today that the order went through and they deducted my money. Went to Macdonald today and they said they cant help me bacause the order was supposed to be collected yesterday tried to explain that I did not know that the order went through since the App was giving me error messages. Macdonald said I must contact MrD to refund me and now MrD is refusing to refund me please help!!!!!!!