<?php
$host = 'https://api.2checkout.com/rpc/6.0/';
$merchantCode = "666999";
$key = "%y~8|m]T84p[W4+O1]_?";
$string = strlen($merchantCode) . $merchantCode . strlen(gmdate('Y-m-d H:i:s')) . gmdate('Y-m-d H:i:s');
$hash = hash_hmac('md5', $string, $key);
$i = 1; // counter for api calls
// call login
$jsonRpcRequest = new stdClass();
$jsonRpcRequest->jsonrpc = '2.0';
$jsonRpcRequest->method = 'login';
$jsonRpcRequest->params = array($merchantCode, gmdate('Y-m-d H:i:s'), $hash);
$jsonRpcRequest->id = $i++;
$sessionID = callRPC($jsonRpcRequest, $host);
var_dump("session id:" . $sessionID);
// call api methods below
$SubscriptionRef = 'B7D8E72224';
$jsonRpcRequest = array (
    'jsonrpc' => '2.0',
    'method' => 'setRenewalPause',
    'params' => array($sessionID, $SubscriptionRef, "2020-09-30 17:00:00", "vacation leave"),
    'id' => $i++
);