It's not in Tortosa but, Rubicalas on the industrial estate in Deltebre, have recently reduced all prices.  They have done work for me in the past. Good quality, clean, solid construction.  I have had doors and windows from them and they were fine.  I am not on commission and have no links with them.
Just thought I would mention them.  I know it's outside Tortosa but it's only 20 mins.