I see, someone should have both those contracts hopefully yours is with your laywers.
You can mail the water company, they will give you the information you need to set up an online account, I had to do the same as I had the same issues when u purchased mine.
Here is the hidrogea website, fill in the help form with your details and an explanation they are very helpful.
https://hidrogea.aguasonline.es/en/inicio