transform string to decimal
The easiest and most clean way would be to use decimal.TryParse() like so  

private decimal ConvertStringToDecimal(string decimalString, decimal defaultReturnValue)
{
    decimal result;
    if (decimal.TryParse(decimalString.Trim(), out result))
    {
        return result;
    }

    return defaultReturnValue;
}  


Using exceptions to control the returned value isn't a good way, especially if there are better methods to use.  

Your indentation is off but I assume that thats a posting issue.