Ben de cümlenizi tam olarak anlayamasam da anladığım kadarıyla ingilizceye çevirdim.

Hello

in the past I have bought a product from you which supports %100 Turkish language pack. However there seems to be a
problem with language pack because I could not use it. When I contact you about the issue you/help desk just said : "we're sorry".
Anyways I want to buy a new product that called "MH290B" could you please check it for me to be sure that offers
%100 Turkish language.

Regards.