I just got unwillingly transitioned from Groove Music Pass. I decided to see how much your service had of my stored music so I used the Groove program to create a new Spotify account. I chose NOT to use a Facebook account, but instead put in an email, password and username.
After it created the account, I came to the website and tried to log in using the username and password. It failed. I then tried my email and password, which succeeded and took me to my account page that showed that I didn't have the username that your sign up form asked me to come up.
Instead, it is 25 alpha-numeric characters. Then I click on Help to see what is going on, and the name in the upper right of the web page switched from garbage to the username I had selected, but going back to the profile page switched it back to garbage.
Then I find out that a username can't be changed. I then read some threads on it on this forum (because the actual help content doesn't mention this issue at all), and saw that you have had this bug for 6+ years, and that the company line is that it's not a bug.
Right now, I'm not sure if I'm going to bother even trying to play music or look into your service any more deeply after this terrible first impression of the quality of it.