I do not approve this attitude

A lovely friend gave me a Konga gift card for my birthday and I wanted to use it with another Konga coupon I already had. But the Konga store did not let me use both of them at the same time. I believe it is nonsense! The online shopping site takes both but does not conclude the payment in the end. But it accepts my gift card with a coupon. I do not want to shop twice from here. They push me for it and it is not ok!.