If To Check The Third Digit

I wanted to write a conditional statement to check if the third digit of a nine digit number is the letter C. Our p.o. numbers are in this type of format (001234567) they always start with two zero's and are all numbers. Except for when they are customer service part numbers, they come in the format of this (00C123456) and sometimes when people enter in part numbers they leave off the two zeros in front.

so it could end up looking like this (C123456) So.... I'm trying to figure out how to write up a conditional statement that says If the third or the first digit is the letter C Then action goes here End If I dont even know what to search for.