Need a consultant to find the performance issues

We are in need of recommendations for an oracle consultant or a consultant company who can manage to solve the following issues that we have had on the production in the past year.

The qualified candidate would be needed to be able to do many things including:

• Review our existing architecture, make suggestions for improvements for both the production hardware and software
• Suggest what patches and settings would better improve performance
• Review past outages, the upgrades and improvements we have made and assess them
• Find the root cause/causes of performance problems that can't be adequately addressed by simply “fix this sql” followed by “fix that sql”, as the problems are more widespread than that.

I think that’s the general idea of the scope of expertise we are looking for. Thanks for your help.