At first glance the question could not be more simple; we write “you contradicted” as we conjugate the verb to say in the second person plural of the present indicative, that is to say. Now, the French language being the one we know, namely pernicious, "to contradict" is not formed exactly like "to say".
The verb "to contradict" is borrowed from the classical Latin contradicere "to speak against (someone, something), to oppose". If at the beginning of the 17th century, "contradict" and "say" (which accepts the meaning "to discuss, blame, criticize") are close enough, their conjugation does not follow today, in the second person plural of the present of the indicative as well as that of the imperative present.
"Contredire" is constructed like the verbs "medire", "predict", "prohibit" as we read in Le Trésor de la langue française. We therefore note that you “contradict”, “meditate”, “predict” in the second person plural of the present indicative.
Attention, the verb "to repeat", always notes the thesaurus, is conjugated as "to say". In this way, we can write: "Tell us more calmly ..."