Shocking efficiency

I am so frustrated with my online order from Birkenstock. On the day of receiving my order I realised it was the wrong size for me and I contacted them immediately. It took THREE WEEKS before I received any confirmation of this return and I was then able to send the item back. I spoke to a customer service representative and told her that I needed to change my order as they did not have the size I wanted. In spite of having the name of a particular representative, and sending an immediate email with a picture of the shoe and size I wanted in exchange, they have gone ahead and processed an exchange of the shoe I do not want. It is beyond frustrating. They do not answer emails and even though I speak in person to representatives, it seems to not make any difference to the outcome. I can safely say that I will never order Birkenstocks online again. I expect that I will now received the incorrect order again, and will again have to process a return. Terribly inefficient customer service.