Standard bank dont value us

I paid using my bank card at shoprite,they swipped the first time it ddnt went through because of network the second time it went through.now when i check my statement two amounts went out for the same transaction,one reflecting as outstanding.i am asking standrd bank to assist reversing the amount i am told they cannot reverse it the merchant needs to call standard bank and i went to shoprite they can only see one transaction that went through. I dnt understand why standard bank is doing this because they can see that it was deducted twice for the same transaction. I am soo disappointed in standard bank