Luxstyle internationalpostbok Sent me an eyelash regrothe liquid, I did not order this but it was sent to me anyway. I am getting letters demanding money including late payment of £10. Internet

 I was looking on facebook and came across an item to grow eyelashes. After looking and deciding that the price was very high for something that may not work. I left the page and didn't think any more about it. I then received an item in the post and it was the item I was looking at but never payed for. I am now getting a letter from them saying that I owe them £44.90 including a late payment of £10 . If I don't pay they will send dept collectors to collect it. I have emailed them and they said I can return the item to them, I went to the site they sent me to to print out a return slip but could not print from my iPad so went onto my laptop to print it out but now cannot get the information to appear. I am very concerned now that I will not be able to return it and keep getting letters from them.