Is it legal for the photo shop to refund the card and deduct the discount? Is it useful to make a complaint call?

The refund of the photo shop card needs to be deducted from the discount. Whether it is legal or not depends on the prior agreement or the preferential terms of the photography shop. If it is clearly stated that only the card can be discounted, of course, the discounted money will be deducted when returning the card. Just as you are not satisfied with the goods you bought at a discount during the discount period, you can't go to the store after the discount period and return them at a price that is not discounted.

I hope to adopt.