Why do sales not return to me?

Unity changed some things just after I made a large purchase in 2013, and I was compensated by a 40% off voucher, with the following text:

******----
As a goodwill gesture, we’ve decided to offer those of you who bought Basic Add-On licenses during the 30-day period prior to Davíd’s announcement a discount on future purchases from the Unity Store.----


When I enter the store, the 40% off one item voucher is there alright. But the system would not allow me to apply it - or I did not know how - it was not very informative, and in order to see the price for the license I had to log in, so it was impossible to compare before / after voucher-price.

March 17, 2014 I wrote to the store about this, and Joana Kodyte auto replied that she’d get back to me within 48 hours… she did not, what happened? NOTHING!

April 17, 2014 I wrote again, same result, auto respond: We will get back within 48 hours… NOTHING!

April 13, 2014 - the licensing is now changed again, so the product I originally intended to purchase is now split up into two, and my voucher only applies to 1 purchase. I wrote to 2 different sales representatives, I gave them my e-mail in the text I wrote as an extra precaution.

I got two auto replies that Unity will get back to me in 48 hours… NOTHING!

Where do I have to write to Unity to get anything but auto-responses?

How much is a 40% off voucher worth if it cannot be applied, and what on earth am I to do now that the item is no longer 1 but 2 (I want to buy Android Pro, but can now only get if I also upgrade to Unity 5 - fine by me, but I am not paying full price, I have been trying to buy the upgrade for months with my Voucher now)

Grr!

Joana has contacted you.