Zara Online Refund Delayed for 20 Days Despite Return Delivery Confirmation

I purchased a dress for ₺3,290 and two pairs of shorts for ₺1,290 each from Zara Online. I returned all the items using the two separate return codes provided by Zara and handed the parcels over to the courier. Although the courier tracking records confirm that the returned items were delivered to Zara, approximately 20 days have passed without any refund. I have contacted customer service several times, but each time I am told that the items have not reached the warehouse, that they cannot assist me, and that I should be understanding. However, I have proof that I returned the items and that they were delivered to Zara, and I do not accept being held responsible for this delay. I request that this issue be resolved promptly and that the full amount of ₺5,870 for the dress and two pairs of shorts be refunded to me as soon as possible.