Diesel Denim Online Disaster

I spent thousands of Rands at the Diesel online store buying 3 pairs of denims but unfortunately 2 of the pairs did not fit correctly. I am now 3 days post refund request and have been told I will Have to wait at-least another 10 days for the courier company to pick up the denims for refund. Why?? This is shocking customer service and I definitely did not expect it from such a large Italian designer chain. I am also not permitted to exchange the denims in store. Why are they offering an online service when they obviously can not handle the after care???