curl --request POST \
  --url https://api-eu.flexportal.io/v1/subscriptions/{subscriptionId}/upgrade \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --header 'Tenant-ID: <tenant-id>' \
  --data '
{
  "rentalId": "<string>",
  "newSku": "<string>",
  "newSerialNumber": "<string>",
  "contractLength": 60,
  "newMonthlyAmount": 1,
  "reason": "<string>",
  "notes": "<string>"
}
'

import requests

url = "https://api-eu.flexportal.io/v1/subscriptions/{subscriptionId}/upgrade"

payload = {
    "rentalId": "<string>",
    "newSku": "<string>",
    "newSerialNumber": "<string>",
    "contractLength": 60,
    "newMonthlyAmount": 1,
    "reason": "<string>",
    "notes": "<string>"
}
headers = {
    "Tenant-ID": "<tenant-id>",
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {
    'Tenant-ID': '<tenant-id>',
    Authorization: 'Bearer <token>',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    rentalId: '<string>',
    newSku: '<string>',
    newSerialNumber: '<string>',
    contractLength: 60,
    newMonthlyAmount: 1,
    reason: '<string>',
    notes: '<string>'
  })
};

fetch('https://api-eu.flexportal.io/v1/subscriptions/{subscriptionId}/upgrade', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://api-eu.flexportal.io/v1/subscriptions/{subscriptionId}/upgrade",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'rentalId' => '<string>',
    'newSku' => '<string>',
    'newSerialNumber' => '<string>',
    'contractLength' => 60,
    'newMonthlyAmount' => 1,
    'reason' => '<string>',
    'notes' => '<string>'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json",
    "Tenant-ID: <tenant-id>"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api-eu.flexportal.io/v1/subscriptions/{subscriptionId}/upgrade"

	payload := strings.NewReader("{\n  \"rentalId\": \"<string>\",\n  \"newSku\": \"<string>\",\n  \"newSerialNumber\": \"<string>\",\n  \"contractLength\": 60,\n  \"newMonthlyAmount\": 1,\n  \"reason\": \"<string>\",\n  \"notes\": \"<string>\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Tenant-ID", "<tenant-id>")
	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://api-eu.flexportal.io/v1/subscriptions/{subscriptionId}/upgrade")
  .header("Tenant-ID", "<tenant-id>")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"rentalId\": \"<string>\",\n  \"newSku\": \"<string>\",\n  \"newSerialNumber\": \"<string>\",\n  \"contractLength\": 60,\n  \"newMonthlyAmount\": 1,\n  \"reason\": \"<string>\",\n  \"notes\": \"<string>\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api-eu.flexportal.io/v1/subscriptions/{subscriptionId}/upgrade")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Tenant-ID"] = '<tenant-id>'
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"rentalId\": \"<string>\",\n  \"newSku\": \"<string>\",\n  \"newSerialNumber\": \"<string>\",\n  \"contractLength\": 60,\n  \"newMonthlyAmount\": 1,\n  \"reason\": \"<string>\",\n  \"notes\": \"<string>\"\n}"

response = http.request(request)
puts response.read_body

{
  "success": true,
  "message": "<string>",
  "oldRentalId": "<string>",
  "newRentalId": "<string>",
  "oldDevice": "<string>",
  "newDevice": "<string>",
  "newMonthlyAmount": 1,
  "currency": "<string>"
}

{
  "error": {
    "code": "<string>",
    "message": "<string>"
  }
}