BT infinity self install - change faceplate on weird master?

I am about to get BT infinity 2, all being well, on Tuesday having been on ADSL previously. It's a self install which I gather is standard now.

Turns out I'd always been using an extension socket getting 5mb/0.5mb or so speeds. Connection always seems stable. Having discovered the master socket behind a cupboard in my son's bedroom (sigh), this went up to about 6mb.

But this master socket seems a bit of a mess. It has a loose dongle of some sort hanging out of the top, which I wonder if perhaps it is the wiring coming in and past another dead master socket (I recall the previous owners of the house had two landlines; presumably this was for the other). There is a lot of wiring concealed within and 2 wires go to port 2 and 2 to port 5 in the master (we have extension sockets in virtually every room although I have never tested them all).

I've removed what I believe to be the ring wire (orange from port 3 and 4) and this increases speed to just over 7mb. Using the test socket goes up to 7.25mb so not a huge difference.

Is there any mileage in buying a Mk3 interstitial faceplate thing - ie, might it improve things (presumably it can't hurt, or can it?) or should I just wait and see first? I'd rather not be mucking around too much post install and seeming to cause errors on the line.

We are using a downstairs extension for the landline.

NB dslchecker suggests I should be getting 4mb download on ADSL so presumably the wiring generally is not too bad, not sure what this means for VDSL though.

pic of dongle thing:
http://imgur.com/sT7wBG7

pic of wires:
http://imgur.com/qmNFt2x

Thanks for any input.

Ideal world - interstitial plate on master and HH plugged in there.

Based on the extensions in every room comment, then two sets of extension wiring leaving the master sounds not unusual.

NOTE If you fit an interstitial faceplate then the ADSL or FTTC modem will not work at any of the extensions