Hi there. Sorry to hear you're experiencing speed issues.
From looking at your download speed of 327mbps it looks like that test you've done is a bit off. Testing your line I can see your router in sync at a downstream speed of 48.9mbps, and upstream of 15.8mbps.
Can you run a BT speedtest at http://www.speedtest.btwholesale.com using a wired connection, completing the further diagnostics at the end? This will store the result on the supplier system and will help us in reporting a fault to our suppliers.
EDIT: If you're using Mozilla Firefox as your web browser, please could you use a different browser if possible when running the speed test?
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