OK so your approach here isn't wrong. You're doing everything the "right way" so to speak by taking a metric that's profitable (Opera Mini) and breaking it out to another campaign to see if you can simply get profit by removing all the other manufacturers.
Unfortunately when you did this it also dropped the ball in terms of ROI. So basically we want to go back to the overall numbers. Is there room for a split test with another landing page? If so then you want to include that. If possible hit me up and have me make the request from the client for a different page or another angle you can take.
If you've split tested all the landing pages and aren't finding a for sure winner then we want to look at your day parting stats. Is there a particular time frame during the week that's working out better? If so then we want to isolate that in a separate campaign and see if the results remain consistent. Also, you want to look at the day of the week. Is there a particular day that's working better than the others? If so, same thing you want to isolate that variable in a new campaign and setup a test. Maybe this campaign is best ran during certain hours of the day or day of the week.
Another area you want to explore is the traffic source. Especially if you're spending good money then go to them and tell them you have a campaign that's working well for you but you're slightly below where you need to be. Let them know if they're able to reduce your CPC then you're able to spend A LOT more. I know in some countries that the traffic sources have direct placements on they'll go lower than $0.01 if you commit to some type of volume.
Finally, you can send me your results to ryan@revivedmedia.net and I can go to the client and see how things are looking on the back-end. I can let them know that you're close to profit but not quite there yet and they may bump you on the offer if you're pushing heavy consistent volume and if it's working on the back end.
The good thing is here you're getting conversions, you have data to work off. The bad thing is you're not yet profitable. So since the operators isn't an optimization for you here we have to work on: 1) the angle 2) time of the day 3) day of the week 4) getting the source to lower the CPC and 5) work with the client.
Let me know your thoughts and let's get that ROI into the black!