Poor service from Makro - online shop has payment shortcomings

I had purchased Makro gift vouchers with the intention of using them to buy a TV that was on promotion. However, when I proceeded to the checkout, the system did not provide an option to pay with gift vouchers. After contacting the support center, I was informed that the system was unable to use vouchers for online purchases. Unfortunately, the promotion ended the same day and I was unable to go to a store to complete the purchase. I decided to pay via credit card and to resolve the matter afterward, which should not be difficult. However, the customer service experience isdisappointing, with only one unsatisfactory reply and no response to subsequent messages. I believe that the gift vouchers should be accepted as payment regardless of the platform used to make the purchase. Overall, the poor customer service experience is frustrating.