Been having trouble using Whatsapp. Previously used Whatsapp on BlackBerry without any problems but since using on the iPhone I don't get notified on new messages when connected via wifi. It always notifies when the app is open but I don't want Whatsapp draining the battery keeping it open all the time. 3G is more reliable in letting me know when I receive messages even when the app in closed but even then, sometimes it's delayed by 5 mins or more which can be frustrating. Awaiting a reply to my tweet sent to Whatsapp earlier on in the week about it but thinking it might be an iPhone/iOS problem. Anyone else having the same issues?