Zara complaint: Return

Hello,
I purchased a pair of jeans, a children’s shirt and children socks. For the first time I used there a new self check out. I gave my email address so that I could receive my receipt via email, but never received the receipt. The day I was there there was an issue with the machines self check out machines and there was two employees helping the customers, so I was helped by an employee. I am not happy with the jeans and so I am returning them, but do not have a receipt.. my purchase was only made two days ago and the jeans still have the tags and we’re never worn. I also have my bank statement that shows the purchase.. the manager in the shop was extremely rude and told me to go online to their chat. Customer service, but that was not helpful at all.. I would like to return the jeans, how can I do that? There is no phone number or email to help customers.. it is very frustrating because I do not want to lose €40 and a pair of jeans that I cannot wear and there is no one to speak to to find a solution. It was not my mistake that I never received a receipt, it was Zara’s mistake.
Thank you