Charge of usd 49.99 we never authorized

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THEY'VE MADE A BIG MISTAKE OR A FRAUD. THEY LOADED ON MY HUSBAND'S CARD, A CHARGE OF USD 49.99 WE NEVER AUTHORIZED.
WE ASK URGENTLY TO INFORM US WHAT HAPPENED AND TO REINSTATE THE AFOREMENTIONED CREDIT CARD THE FULL AMOUNT DISCOUNTED.
BESIDES, I DON'T UNDERSTAND WHERE THEY GOT THE NRO. CARD IF WE'VE NEVER MISSED IT.
THIS SETS UP A VERY SERIOUS PROBLEM FOR US.
WE EXPECT QUICK RESPONSE AND IN OUR LANGUAGE.
LUZ RODRÍGUEZ-EASTERN REPUBLIC OF URUGUAY