C# Reading CSV data with correct cell format using Regex

C# Reading CSV data with correct cell format using Regex.

I am facing issue with CSV cell format.

My excel data is as below:

Date      |    Acct    |  Name
20210928  |  3.02+ 13  | ABC

where Acct is 14 digit number. But Acct number is displayed as in above format.

Code for reading excel data is as below:

var csvlines = File.ReadAllLines(file);
Regex CSVParser = new Regex(",(?=(?:[^"]*"[^"]*")*(?![^"]*"))");
var csvLinesData = csvlines.Skip(1).Select(l => CSVParser.Split(l).ToArray());

With this code, CSV comma separated cells value will be added in Array.
But here for Acct field data is getting fetched as “3.02+ 13” but I need it as 14 digit number

How can I do that in above code? any thing to do with Regex?