Unreliable Speeds & Service!

I’ve been contacting for support on various occasions utilizing the Home-Connect App, but still experiencing very low speeds. I’ve ordered the 50Mbps fibre package, but the download speeds are continually below 30Mbps! When the remote support personnel checked via the HC diagnostic App, they’ve discovered that the actual broadband speeds only reached 12Mbps! They then downloaded an update on the router, but I’m still experiencing fluctuating low speeds. Service is very bad considering that I’m constantly sending them proof of these low speeds when registering the service complaints.