I have an ASP.NET MVC project where I need to follow to open closed principles.

The project converts a .csv file to a model from database, but in the future we might have to convert excel files too to the same model from database.

Now, I have this code in Convertor class:

public class Convertor 
{
    private static ICompanyRepository companyRepository;

    /// <summary>
    /// converts the uploaded csv data to Company model
    /// </summary>
    /// <param name="filePath">the csv data</param>
    /// <returns>a list of Compamy model</returns>
    public List<Company> ConvertCsvToCompanyModel(string filePath)
    { 
        companyRepository = new CompanyRepository(new ImportContext());
        List<Company> companies = new List<Company>();

        //Read the contents of CSV file.
        string csvData = System.IO.File.ReadAllText(filePath);

        //we skip the first row, because it contain the header         
        var csvLines = csvData.Split('\n').Skip(1);

        //Execute a loop over the rows.
        foreach (string row in csvLines)
        {
            if (!string.IsNullOrEmpty(row))
            {
                if (!companyRepository.CompanyExist(row.Split(',')[0]))//check if already contains the ExternalId
                {
                    companies.Add(new Company
                    {
                        //CounterPartId
                        ExternalId = row.Split(',')[0],
                        //Name
                        TradingName = row.Split(',')[1],
                        //IsBuyer
                        IsForwarder = Convert.ToBoolean(Enum.Parse(typeof(BooleanAliases), row.Split(',')[2])),
                        //IsSeller
                        IsCarrier = Convert.ToBoolean(Enum.Parse(typeof(BooleanAliases), row.Split(',')[3])),
                        //Phone
                        Phone = row.Split(',')[4],
                        //Fax
                        Fax = row.Split(',')[5]
                    });
                }
            }
        }
        return companies;
    }
}

Can you please give me some hints how to change this code? in order to follow the open closed principle. In the future as I mentioned it is possible to need a converter for excel files, too. Thanks.