Arduino Mega Multiple Serial device integration

I need you to develop some software for me. I would like this software to be developed using C or C++. I have already written most of the progrm however I have some debug issues to resolve The Arduino code C++ collects multiple serial and I2C data streams and then steers a robot using a Sabertooth 32*2 motor controller. The Adruino mega is commected to a gps, 2 compasses (one seria and one I2C) a LCD screen and SD card reader. The software works however I am having some trouble with the serial compass intergration. You must be a proven professional C++/Arduino programmer. Please only apply if you live in the UK (Europe or USA). I travel between the two countries so comms is easy. I do not wish to work with programmers on a different time zone or have other communication issues. You need to have experience of the Arduino mega and interfacing multiple serial devices with different baud rates to produce consistant and acurate output