Not only the CPC is a parameter to get a good position but also the relevancy between the Keywords, the ads and the destination URL
I would advise you to use dynamic text to increase your position.
You can at a second point create other ads.
In general, you should success to get the first position by increasing the high bid. If it is not the case, you should contact the support team of adCenter. They have the possibility to investigate further this issue.
I hope this help
Pierre