The CsvOptions allows you to change encoding, delimiters, qualifiers, extension, and line break of a CSV exported document. You should set the customization properties in the CsvOptions property of Report Writer instance.
writer.CsvOptions = writer.CsvOptions = new BoldReports.Writer.CsvOptions()
{
Encoding = System.Text.Encoding.Default,
FieldDelimiter = ",",
UseFormattedValues = false,
Qualifier = "#",
RecordDelimiter = "@",
SuppressLineBreaks = true,
FileExtension = ".txt"
};