YOU SAID:
never was i so disappointed
INTO JAPANESE
こんなにがっかりしたことはなかった
BACK INTO ENGLISH
I've never been so disappointed
INTO JAPANESE
こんなにがっかりしたことはありません
BACK INTO ENGLISH
I have never been so disappointed
INTO JAPANESE
こんなにがっかりしたことはありません
BACK INTO ENGLISH
I have never been so disappointed
That didn't even make that much sense in English.