Character Frequency Sorter

You are tasked with analyzing the frequency of characters within a given string. Your goal is to implement a method GetCharacterFrequencies that takes a string as input and returns a list of KeyValuePair<char, int> objects. Each KeyValuePair should represent a unique character and its total count within the input string.

The analysis must adhere to the following rules:

• Case-insensitivity: Treat uppercase and lowercase letters as the same character (e.g., 'A' and 'a' should both contribute to the count of 'a').
• Sorting: The resulting list must be sorted primarily by frequency in descending order. If two characters have the same frequency, they should then be sorted by the character itself in ascending alphabetical order.

Your starter code contains placeholders and a bug that need to be addressed to correctly implement this functionality.