I switched to SnapEngage, which also has a proactive chat feature that lets you automatically initiate chats on certain URLs and such. It just worked and, I think, was cheaper too... been using it ever since.
I don't actually spend many hours online available to chat, so most of the time the little widget in the corner of the page says "Live Support Offline" and clicking it pops up a contact form instead of a chat. I get mails from that every day, where almost nobody used the contact form built into the websites. It's worth the $19/month just for that.
I'm assuming Olark has long fixed those issues I ran into, but I've no reason to want to switch back now.