Slow Unlimited Fibre Extra around 15 mbps

[#1]

Since I moved flats, but with my Phone Line from the same junction box in the same building, my Unlimited Fibre Extra started off around 45mbps download but has now come down to around 15mbps. My new service here started around 6 weeks ago, so the DLM has had time to recognize the fastest stable speed for my line., so I wonder if there is a minor fault on the line. I use a BT SMART HUB and at the previous flat, I often got speeds in excess of 70mbps. I am using Ethernet to my PC and I used Broadband Speed Checker to find the speed. I have also just replaced the Line Filter and the cable to the router today, but it still shows Ping 22 ms. Down 15.30 Mb/s. Up 7.42 Mb/s. I am new to the forum, due to an excellent service up till now.
What should I do?

[#2]

I have since had a Tech check the line with the Albert troubleshooting steps. This was around 17:00 today, and he has increased the Decibels on the line, and has asked me to do a factory reset on my Smart Hub (6) at around 20:30 this evening. Since we spoke, my speed has got worse, now at 14mbps. However, looking at the hub, the Broadband Connection Page tells me I have a speed of 69.10mbps Downstream and 20mbps upstream. Maybe that is the maximum, or max average I got since I first used it. Does anyone know about that?

[#3]

The problem is now resolved.
I had some wireless items too near it, my Dect Base Station and a Bluetooth Mobile Phone to Landline connector, which halved my Mbps, so try not to have any other wireless items too near.
I apologize for such a silly mistake, but I hope it will help some others with the same problem.