Disappointing to hear that this is still ongoing, charlesb73.
I'm afraid there isn't much we can do here on our public forum. Can only confirm previous responses that you'll need to report a fault, if you've received an unsatisfactory responses you can request to escalate to a Manager and go from there.
I have already contacted Optus Support two days ago regarding the mobile reception/speed issue, and it ended up with a coverage check that showed Runcorn has 3G/4G, and that perhaps my phone (model) and my Optus sim card may need to be tested. And that I need to provide a specific address (even when I said that I don't live in the area).
I said that I have 4 mobile phone services between my family members with different phones (iphones and samsungs), as well as the mobile reception speed is at least >150 Mbps in others areas, whilst in Runcorn my speedtests show a download speed between 0 and 1 Mbps. I have screenshots.
Optus should contact their mobile customers who live in Runcorn to test their mobile reception speed. Most who live there would probably use their home wifi, the biggest pain will be to customers like myself who are in Runcorn often but don't live there, hence we use mobile data rather than home/office wifi. I'll contact Support again and report a fault.
I can also confirm that I had three other Optus mobile users who frequently come to Runcorn area, that they have the same slow speed issues on mobile. I have taken a video, demonstrating the slowness on two mobile phones side by side.
Submitted an Optus Fault on the 28 Feb 2020, received an SMS that I will be contacted within 24 hours, and today is 6 March 2020, I haven't received any comms or call.l