Resolve coding issues - Arduino Program for 4x4 RC car

Hi All, I need assistance fixing some coding for an Arduino project. I have coded what I can but am struggling to get other things working. I have listed below what I have got working, what is not working, and what is not coded. I expect the stuff that is not working, and not coded to be done, so I end up with a working project as described here: ====================================== Here is what I am doing: I am building a 4wd remote control lawnmower (based on an older style 4x4 mobility scooter). So we have a 4wd chassis, with 4 motors. The chassis will drive in both skid steer and servo turn modes. I have already build the majority of the code, however some aspects are not working together very well. Here is how it is expected to function, and also what I have coded so far: When pressing forward on the joystick, both the left-hand side and right-hand side motors will move forward. (Coded and working) When pressing backwards on the joystick, both the left-hand side and right-hand side motors will move reverse. (Coded and working) When pressing left or right on the joystick, this will in turn move the steering servo connected to the front wheels. (Coded but NOT working. This seems to interfere with other code and does not work currently) When pressing the left button, skid steer will activate and move left-hand side wheels in reverse, and right hand side wheels forward. (Coded but NOT working. This seems to interfere with other code and when button is pressed the motor controller lights up, but only very weakly and motors do not spin...weird! ) When pressing the right button, skid steer will activate and move left-hand side wheels in forward, and right hand side wheels reverse.(Partially coded but NOT working. This seems to interfere with other code and when button is pressed the motor controller lights up, but only very weakly and motors do not spin...weird! ) ====================================== I also expect the following safety features added to the program: PIR sensor; If the PIR detects anything, it stops all wheels, and will also trigger a relay which will disengage the ignition circuit, forcing mower motor to stop also. (NOT coded) Temp sensor; If the tempo sensor detects temp range above X, same as above, stops chassis and mower (via relay to ignition)(NOT coded) ====================================== I have a basic schematic of how the current benchtop setup is wired. I am using a freetronics Eleven (same ad UNO) and a funduino joystick shield V1.A for the controls. The final setup will use TWO motor controllers for 4 motors in total. 1 controller for the left motors and 1 controller for the right motors. I expect ALL lines to be commented properly so I understand what needs changing if future. I expect each section to be commented too. For example, Forward, Reverse, Steering, PIR, etc. That's about it in its simplest form to try and explain what I am trying to program here ... In a nutshell I need help fixing this code so I can move forward with the project. Please read code before bidding, and check schematic to make sure you are comfortable. I will work with you, uploading revisions to test if issues and additions are now working.