SoftwareSerial mySerial(1, 0); // RX, TX
You can't do software serial on the hardware serial pins.
The Message is a string that
No, it isn't. It's a String. BIG difference.
if(xPosition !=-1){
Don't you think it would be a good idea to test this BEFORE you assume that you can use it to define the length of a substring?
Three strikes. I quit reading.