Had to register just to say thanks for such a great and informative thread

I guess I'm pretty much typical in that last week I noticed a drop in my speeds. But mine were coupled with some contractors turning up to replace the telegraph pole outside our house. We live on the side of a steep hill and it has been leaning for some years now and each year it gets inspected. Finally back in January we got notice that it would be replaced in the next 10 days (yeah, go figure!) and I was dreading the day.
I work from home, permanently, and internet is critical for me as I manage a virtual infrastructure remotely. I had previously had a rock solid sync rate of 80001 d/l since FTTC came to the town in October 2014. So I was dreading some grease monkey pulling that pole out of the ground. And of course, my fears came true. Initially I noticed them packing up to leave so I stuck my head out the window and asked when my line would be back on. I was of course greeted with the expected puzzled looks, phone calls and the ladder coming back out the van. 20 mins later we're back up and running and "yeah, sorry, these new modules are crap" comment. next day someone else goes up the pole and the line goes off again, a similar story takes place.
So don't get me wrong 80Mbit as it was is fine, 59Mbit as it became is still pretty good but it irked me that I'd lost 25% and yet was still paying 100% so I contacted Zen (my ISP) who were OK but I'll admit not as great as usual. I do remember them saying something about waiting on a firmware upgrade from BT but it still didn't seem right.
Bear in mind through all of this I'm on an ECI modem that is locked so the only way I can see my sync rate is from Zen's portal "line data" and right now, that is no longer updating since the 59079 rate. Today, I look out the window and spot another chap up the pole. These modules must be really poor! I wonder across the road and explain my (roughly) 20Mbit drop and he says he'll take a look and join the wires directly.
So now from d/l rates on speed checker's I think I'l back to around 70Mbit, so I'm hunting around for further info and if I'm honest, I think I have arrived at the conclusion that I'm probably now also effected by G.INP. I can see that totally unrelated to the 'pole' incident my line went down to 71858 on 31st March.
I've put a cheeky punt on a Huwai VDSL modem on eBay but beyond that there's not much I can do but keep an eye on things on here.
I never intended to spend the evening reading up on this but I'm glad I did.
Unfortunately only last year my ADSL router gave up and I bought a TP-Link 8980, otherwise I'd probably go and buy a 9890 as I do link TP-Link's service. Will sit tight for now though.
Sorry for the rambling reply...
[EDIT] Oh, no idea what kit is in our green box. Now I've also seen the pictures I may take a walk at the weekend. I know where the box is...