Koovs.com - Order not delivered.

I ordered a pair of sandals from koovs.com on the *th of May. The site told me it would be delivered by *th while also adding that the actual time may vary. I got the order on **th of may. The sandals were large for me so I decided to get an exchange. I filed for it on the **th because that is when it showed that the product was delivered. I waited everyday for it to be picked up, called the courier company who told me to wait till **th. On **th it was picked up from me. Today its **st May and I have been calling koovs customer service helpline almost everyday. They tell me to wait for ** hours assuring me that they will call me but they don't. I get the same prototype answer everytime I call them. They tell me that have prioritized my issue and will look into it but nothing is happening. I called them today(Friday) and they asked me to wait for Monday. I feel cheated and violated by koovs.com. I don't know what to do and where to go regarding my complain. I am mentally exhausted.