Nobody picking up the telephone number to exchange my size

Hi there, I bought Bathu online with Pay Just Now app it was delivered on Friday the 2nd of July ... And the size I got is too small it is size 7 and I actually need to change to size 8.. On my emails I cannot find the receipt but I still have everything else. I have tried to call all your numbers of the card I got inside and no one is picking up.

I am panicking because it is written I cannot return it after 7 days.. Please respond advise me on what I can do because Durban is too far to go directly.

Please advise on what I can do at this point as my seven days is ending today.