I've come back in this morning to a response from the previous engineer who visited.
He's apologised that you're still having problems and has advised that he'll figure out the best course of action with management to arrange another appointment. He's also said that he'll get in touch with the network experts to refer your case.
This sounds like the best plan to me, could you keep me posted with how everything goes? If you don't hear anything, I'll chase this again for you.
Thanks for getting back to me and confirming this information. It was Mike who emailed me to confirm that Network have now cleared things, but I'm sure he can go into more detail with you when you next speak. He did say he'd keep both me and you in the loop so I'm confident you'll hear from him again soon.
If you do go a little while without any contact, please reach out to me so I can chase this for you.