diff --git a/ci/output-results-to-slack.yaml b/ci/output-results-to-slack.yaml
index 034c802..f5bb377 100644
--- a/ci/output-results-to-slack.yaml
+++ b/ci/output-results-to-slack.yaml
@@ -10,6 +10,7 @@ params:
   OUTPUT_BUCKET:
   OUTPUT_DIR:
   SLACK_CHANNEL_NAME:
+  SLACK_CHANNEL_ID:
   NUMBER_OF_DAYS:
   SERVICE_ACCOUNT_JSON: ((gcp.service_account_json))
   SLACK_AUTH_TOKEN: ((eq-ons-slack-app.bot_user_oauth_token))
diff --git a/scripts/slack_notification.py b/scripts/slack_notification.py
index 3301a8f..4956372 100644
--- a/scripts/slack_notification.py
+++ b/scripts/slack_notification.py
@@ -17,6 +17,11 @@ def parse_environment_variables():
         print("'SLACK_CHANNEL_NAME' environment variable must be provided")
         sys.exit(1)
 
+    slack_channel_id = os.getenv("SLACK_CHANNEL_ID")
+    if not slack_channel_id:
+        print("'SLACK_CHANNEL_ID' environment variable must be provided")
+        sys.exit(1)
+
     content = os.getenv("CONTENT")
     attachment_filename = os.getenv("ATTACHMENT_FILENAME")
     if content and attachment_filename:
@@ -42,6 +47,7 @@ def parse_environment_variables():
     return {
         "slack_auth_token": slack_auth_token,
         "slack_channel": slack_channel,
+        "slack_channel_id": slack_channel_id,
         "content": content,
         "attachment_filename": attachment_filename,
         "file_type": file_type,
@@ -50,26 +56,6 @@ def parse_environment_variables():
     }
 
 
-def get_channel_id(client, channel_name):
-    try:
-        conversation_data = client.conversations_list()
-        if not conversation_data.get("ok", False):
-            print("Failed to fetch channels")
-            sys.exit(2)
-
-        channels = conversation_data.get("channels", [])
-        for channel in channels:
-            if channel.get("name") == channel_name:
-                return channel.get("id")
-
-        print(f"Channel: '{channel_name}' not found")
-        sys.exit(1)
-
-    except SlackApiError as e:
-        print(f'Error fetching channel list \nError: {e.response["error"]}')
-        sys.exit(2)
-
-
 def post_slack_notification(
     slack_auth_token,
     slack_channel,
@@ -78,14 +64,16 @@ def post_slack_notification(
     file_type,
     initial_comment,
     title,
+    slack_channel_id,
 ):
     client = slack.WebClient(token=slack_auth_token)
-    slack_channel_id = get_channel_id(client, slack_channel)
+
     try:
         if content:
             response = client.files_upload_v2(
                 channel=slack_channel_id,
                 content=content,
+                filetype=file_type,
                 title=title,
                 initial_comment=initial_comment,
             )
@@ -93,6 +81,7 @@ def post_slack_notification(
         else:
             response = client.files_upload_v2(
                 channel=slack_channel_id,
+                file=attachment_filename,
                 title=title,
                 initial_comment=initial_comment,
             )
@@ -113,4 +102,4 @@ def post_slack_notification(
         warnings.simplefilter("ignore", category=RuntimeWarning)
 
         parsed_variables = parse_environment_variables()
-        post_slack_notification(**parsed_variables)
+        post_slack_notification(**parsed_variables)
\ No newline at end of file