SQL API call through sp_OAMethod causing error - sql

Question

I'm looking to add an item to our systems through an API call to the supplier's site on given conditions. We have a replicated database and I want the process to be automated.
The supplier's, surprisingly, require you to login on one address then navigate to another to call the SEND but I don't think that the session is being persisted.
The code below is the SP I'm trying to create, which would allow me to use it for a variety of updates, not just this specific type.
The code I have so far is:
CREATE PROCEDURE [dbo].[CallAPI]
(
#Address nvarchar(MAX)
,#Message nvarchar(MAX)
)
AS
DECLARE #url_login nvarchar(MAX) = 'https://credentials'
DECLARE #Login nvarchar(MAX) = '{"username": "uSeR","password": "pAsS"}'
DECLARE #obj int
DECLARE #hResult int
DECLARE #statusText varchar(1000)
DECLARE #status varchar(1000) = 200
---------------------------------------------------------------------------------------------------
EXEC #hResult = sp_OACreate 'MSXML2.ServerXMLHttp', #obj OUT
---------------------------------------------------------------------------------------------------
--Log in
EXEC #hResult = sp_OAMethod #obj, 'Open', NULL, 'post', #url_login, false
EXEC #hResult = sp_OAMethod #obj, 'setRequestHeader', NULL, 'Content-Type', 'application/json'
EXEC #hResult = sp_OAMethod #obj, 'setRequestHeader', NULL, 'api-key', 'APIKey'
EXEC #hResult = sp_OAMethod #obj, 'setRequestHeader', NULL, 'connection', 'keep - alive'
EXEC #hResult = sp_OAMethod #obj, 'setRequestHeader', NULL, 'cookie', 'monster'
EXEC #hResult = sp_OAMethod #obj, 'send', NULL, #Login
EXEC sp_OAGetProperty #obj, 'StatusText', #statusText out
EXEC sp_OAGetProperty #obj, 'Status', #status out
IF #status = 200
BEGIN
print 'Successful log-in'
-------------------------------------------------------------------------------------------
--Navigate to required address
EXEC #hResult = sp_OAMethod #obj, 'Open', NULL, 'post', #Address, false
EXEC #hResult = sp_OAMethod #obj, 'setRequestHeader', NULL, 'cookie', 'monster'
EXEC sp_OAGetProperty #obj, 'StatusText', #statusText out
EXEC sp_OAGetProperty #obj, 'Status', #status out
IF #status = 200
BEGIN
-----------------------------------------------------------------------------------
--Post message
print 'Successful navigate'
EXEC #hResult = sp_OAMethod #obj, 'send', NULL, #Message
EXEC sp_OAGetProperty #obj, 'StatusText', #statusText out
EXEC sp_OAGetProperty #obj, 'Status', #status out
IF #status = 200
print 'Successful posting'
END
END
IF #status <> 200
SELECT #status, #statusText
EXEC sp_OADestroy #obj