Web scraping beginner. AJAX POST request not working - ajax

Question

I have just started out with web scraping.
The data I need seems to be returned by an AJAX POST request. POST requests are very rarely covered by scraping tutorials and seem to come with lots of "gotcha's" for new users like myself.
I copied the request from Chrome dev tools into Postman using cURL and then generated the Python request code. The request uses a peculiar set query parameters... I have however repeated this process and the only parameter that changes is the session ID.
The problem is that the request stops working after some time has elapsed (Internal server error 500). I would then have to copy the request from the site again with the new session ID.
Any pointers in the right direction would be appreciated.
import requests
url = "https://online.natis.gov.za/gateway/PreBooking?_flowId=PreBooking&_flowExecutionKey=e1s2&flowName=[object%20Object]&_eventId_next=Next?dtoName=perSummaryDetailDto&viewId=perSummaryDetail&flowExecutionKey=e1s2&flowExecutionUrl=%2Fgateway%2FPreBooking%3F_flowId%3DPreBooking%26_flowExecutionKey%3De1s2&sessionId=IWhelPTLyYDa7JohJV6x8So_qEKdC8wOknArAXkS&surname={SURNAME}&initials=R&firstName1={FIRSTNAME}&emailAddress={EMAIL}&cellN={CELL}&isWithinPriorityDate=false&viewPrioritySlots=false&showPrioritySlotsModal=false&provcdt=4&supportUser=false"
payload = {}
headers = {
'Connection': 'keep-alive',
'Content-Length': '0',
'sec-ch-ua': '" Not;A Brand";v="99", "Google Chrome";v="91", "Chromium";v="91"',
'Accept': 'application/json, text/plain, */*',
'sec-ch-ua-mobile': '?0',
'User-Agent': 'Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/91.0.4472.114 Safari/537.36',
'Origin': 'https://online.natis.gov.za',
'Sec-Fetch-Site': 'same-origin',
'Sec-Fetch-Mode': 'cors',
'Sec-Fetch-Dest': 'empty',
'Referer': 'https://online.natis.gov.za/',
'Accept-Language': 'en-US,en;q=0.9',
'Cookie': 'JSESSIONID=IWhelPTLyYDa7JohJV6x8So_qEKdC8wOknArAXkS.master:gateway_3; Gateway=R35619282; ROUTEID.33f40c02f95309866c572c0def16f016=.node1; JSESSIONID=BadmtwJ7c8YWEz73xe6Wu165Q7gapmm4WTY6at-p.master:gateway_3; Gateway=R35619282',
'dnt': '1',
'sec-gpc': '1'
}
response = requests.request(
"POST", url, headers=headers, data=payload, verify=False)
print(response.text)