They already replied to my message and (see attachment). I wrote them again but they have not answered me yet.

(This will sound more natural and native) "They already responded and I have that email attached here, but after I replied back they never got back with me." **This is a lot more natural sounding because it is fairly straightforward and I would say more American sounding. Heinz's answer is correct, but it sounds a bit too proper, if you know what I mean.