takealot double charged me and has not responded to me after querying.

I had placed an order through the takealot app, it was paid for and delivered. For some reason the takealot app did not pick up my payment and had my account as an outstanding balance. I had to pay the amount again before I could place my next order. i therefore paid twice for the same order. Takealot has not picked it up nor have they responded to my query.