I used Zalando for years (50+ orders) and I was very happy with them until recently, when returns were not being registered or took very long time to be registered, but a customer service always helped me out, so big “+” to them. On the down side, you always ALWAYS have to save a receipt from Posten as a confirmation of the return, otherwise you get no help.
Lately I discovered that I can no longer get buy stuff with faktura or pay with my bank/credit cards or PayPal, but I have to do an advanced bank payment. WT,F?! In the era of online shopping and dozens of online shops this is just ridiculous. So now, Zalando totally lost me as a customer.