“True pays off”

Hello! Yesterday with the post office I received a “Treuegutschein” over 250€, which I can use if I decide until 30.4. for a 159er. Wanted to ask if one of you has already had experience with the use of this note. In particular I am interested whether this note is to be understood as such a kind of “fixed discount” (which would not be useful, since I am already beyond this amount at the current state of my negotiations) or whether this note is zusäzlic h can be used for the purchase for possible already negotiated discounts – quasi like cash. Thanks for your opinions!