The trouble is that the Plusnet CEO is almost certainly junior to the CEO of Openreach in the BT Group hierarchy, simply because Openreach is far more important than Plusnet.
Plusnet is in fact a customer of Openreach with no more official power over OR than any other ISP. (Ofcom strict rules).
The only real clout available to you is the BT Group CEO, as I suggested earlier. I accept your statement it is Plusnet's problem to resolve it for you, and agree you should now wait to see if anything good comes of your latest reply from Andy Baker. But if that fails, the Group CEO's office is all you have available, and I suggest better tried before moving to another ISP. (Assuming AAISP is outside your price range).
The point of someone above the Openreach CEO getting involved is that engineers can be instructed to get it fixed. For instance, on a standard pair swap the time allowed for the job is fixed so any working pair might be chosen. I think it possible in a High Level Complaints case they may be given the instruction and time to check for the best available. On top of any deeper checks they may be able to carry out. I could of course be wrong there in the detail, but as I also said earlier this path has worked many times where all else failed.
Kindness isn't going to cure the world of all its awfulness but it's a good place to begin. Daisy Ridley.
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