Can I add a third tablet of Diuver 10mg per day on sudden diuresis stop if I have dilated cardiomyopathy and have been taking it twice a day for two years?

Do not increase the dose of Diuver (torasemide) on your own without talking to your doctor, especially if you have dilated cardiomyopathy. Taking Diuver (torasemide) at a dose of 10 mg twice a day for dilated cardiomyopathy is a relatively high dose.

Any modifications in the therapy of cardiomyopathy treatment should be made after consultation with the attending physician who is familiar in detail with your health condition and blood pressure values. We wrote more about it here:

https://www.gdziepolek.pl/artykuly/czy-jak-i-kiedy-mozna-odstawic-leki

A sudden stop of diuresis may indicate a deterioration in health, requiring medical evaluation. If you have any further doubts, it is worth consulting your attending physician. If you are unable to consult your doctor, you can use the teleconsultation here:
https://www.gdziepolek.pl/telekonsultacja/z-kardiologiem

The availability of Diuver in pharmacies in Polish can be checked at the following address: https://www.gdziepolek.pl/produkty/24027/diuver-tabletki/apteki