Royal Mail Return to Sender

LinaM1997

Hi All, 

I am very new and I apologize if I am posting incorrectly. 

I made an order from US to UK and there was no tracking available so after some time I contacted the company and they said they also can't track it or help me so they decided to send a replacement for me and to wait until the 29th Nov and contact them if it does not arrive. The first package arrived about 3 days ago and I just left the case, but today I received a grey note for customs for a new package where the customs are about 160+ pounds. I checked and it is the replacement package which I do not need, so I hurried and selected to return it online with a reason "didn't expect the charge". 


My questions is, will I be charged now for any of the return/customs fees or do I need to do anything else regarding this second package? 

Thank you!