How to save a dictionary to a csv where each key has a different row

import time
import csv

def file_reader():
    product_location = {}
    location = 0
    with open('stockfile.csv', mode='r+') as f:
        reader = csv.reader(f)
        #next(reader) Can be included if I have headers to skip it
        products = {rows[0]: (rows[1],rows[2],rows[3],rows[4],rows[5]) for rows in reader}
        global products
    with open('stockfile.csv', mode='r+') as f:
        for line in f:
            lines = line
            print(lines)
            product_location[line.split(',')[0]] = location
            global product_location
        f.close()    

    total=0
    with open('stockfile.csv','r+') as f:
        for line in f:
            product_location[line.split(',')[0]] = location
            location += len(line)
total = 0
while True:
    file_reader()
    GTIN = input("\nPlease input GTIN or press [ENTER] to quit:\n")
    if GTIN == "":
        break
    if(GTIN not in products):
        print("Sorry your code was invalid, try again:")
        continue

    row = products[GTIN]
    description = row[0]
    value = row[1]
    stock = row[2]
    additional_stock = row[3]
    target_stock = row[4]

    print("Updating stock levels back to target level")
    stock = int(stock) + int(additional_stock)

    print('GTIN: ', GTIN)
    print('You have selected: ', description)
    print('The price of this product is: ', value)
    print('Stock: ', stock)

    quantity = input("Please input the quantity required: ")
    new_stock = int(stock) - int(quantity)

    if int(quantity) > int(stock):
        print("Sorry we don't have enough in stock please order again")
        print("Please try a different product or a smaller quantity: ")
        continue
    else:
        new_stock = int(stock) - int(quantity)
    if int(new_stock) < int(target_stock):
        answer = input("The stock is below target, if you would like to top up the product to the target stock level press [ENTER]")
        if answer == "":
            required = int(target_stock) - int(new_stock)
            added_stock = input("This is the target stock: %s, you must enter a minimum of %s" % (target_stock,required))
            stock= int(new_stock)+int(added_stock)
            while int(stock) < int(target_stock):
                print("Sorry input more please:")
                continue
            if int(stock) > int(target_stock):
                additional_stock = 0
                products[GTIN] = row[0],row[1],str(stock),str(additional_stock),row[4]
                print(products[GTIN])
                print(products)
                writer = csv.writer(open('stockfile.csv','w',newline=''))
                for key, row in products.items():
                    writer.writerow([key, value])

    else:
        additional_stock = int(target_stock) - int(new_stock)
        #I need to do the same here and change the dictionary and then send it to the CSV

        product_total = (int(quantity) * int(value))
    total = total + product_total
print('Total of the order is £%s' % total)

I am unable to work out how to send the dictionary back to the csv with this format (this is the format it is in when it has been called upon at the start and I want to send the information back in the same way). This is what the stockfile looks like: This is the format I want the dictionary to be sent back in as well as when it is opened. Please post the code as well which works and thanks in advance.

How to save a dictionary to a csv where each key has a different row