Brevo PushOwl: Email,Push,SMS

Worse app ever which I did not choose to use but Brevo (which I was using) imposed in my Shopify store. No explanations, no tutorials. I have lost all new contacts because the double opt-in process was removed without informing me. Pushowl help centre is not customers-oriented, using a language only they can understand, so you are left with no help and no solutions. I am extremely upset