LOG IN ISSUE

I recently created an account with WordPress. As this a new blog, the domain (www.subitelabragueta.com.ar ) is still under certification. This is the reason why I set up the account using the “alternative domain” (https://subitelabragueta.com.ar.elserver.com) facilitated by the host provider (www.elserver.com). I could only accessed one time to the blog, actually the first time when the account was generated.
Now, I ‘am not able to access the blog, in order to log in I used this link: https://subitelabragueta.com.ar.elserver.com/wp-login.php, then I entered the username + password (detailed below) and the site is inmediatly directed to https://subitelabragueta.com.ar/wp-login.php, so it not works.
As I remember, at the very beginning I was surfing trough the differents blog’s settings and configuration tools and I tried to change the url from https://subitelabragueta.com.ar.elserver.com to https://www.subitelabragueta.com.ar but WP did not allow me to complete that change, so I assume that no change was made in relation to the url.
At this point I cannot log into my WP account, I will really appreciate if you can assist me on that and solve this issue.