Incorrectly charged courier fee on return

I ordered Jeans online, delivery was made, but size was not right for me. I logged a return the same day of delivery. Item was collected, and I was subsequently refunded for the amount, but was incorrectly charged a courier fee for the return. According to consultant I spoke to, this charge was validated as being incorrect and that I needed to be refunded. I was told to expect a call back. I also logged an email the same night, and got a reference number. It’s been a week and no response. Call centre does not even allow me to speak to anyone. I will not shop online at this store ever again, safer to just buy from other stores that stock Levi’s.