Modify Data in CSV data in Powershell

An automated system, which I cannot modify directly, produces a CSV file to update products on my website, this is done at regular intervals throughout the day in time spans as few as every 15 minutes to the point that manual file intervention is not feasible. We have an immediate need to modify some data based on criteria in the file prior to upload. I need a Windows Powershell Script to: (1) When called, read the CSV file ([login to view URL]) (2) when the column / field VendorNum = 203214 (ideally, a list of numbers but one number is sufficient), change the value of the column/field visibility from 4 to 2. (3) save the file back onto itself using the same name. (4) leave all other records the same - the source file path and file name will always be the same ([login to view URL], the csv file and the script can/will live in the same directory) - there is no requirement to log or output a list of records change - needs to run without user intervention, will be run automatically through part of a larger automated task scheduler sequence - must maintain escaped strings where present, string data may have commas, html characters and occasionally special characters within the codeset of the file (this is rare). - field order must be maintained. The attached / uploaded file is a sample from a larger data set which has representative records. I can/will supply a full normal data set to the person who takes this project on. Validation and Testing I have to upload to our website data processor.