Cashier laughed with customer for my “insufficient funds”

Went to the spar at Radiokop yesterday and my card declined for insufficient funds. I immediately called my husband and he transferred funds within a minute to me . The lady standing behind me asked the teller why am I taking long . So between the cashier and the customer , they had a good laugh at me for insufficient funds. Your staff have no customer service experience. I didn’t appreciate being treated that way .