Panteen in Australia too. They don't do French over here, so the accent on the first e means nothing.
Does it actually have an accent on the name?
I remember the Kelly Le Brock ads in Australia, so the product was introduced as Panteen - which, without any accents, is logical.
Tresemme, on the other hand, used some sort of cod French pronunciation, which probably was a tie-in with the jokey way it was promoted.