Trying to make sense of this speed change.

Question

Ok, I'll try and make this clear, and then see if someone can explain to me why I should put up with this.
I've had BT Infinity since November 2011 and was on the option 2 40mbps connection, and for the last 14 or so months I've had very few issues and CONSISTANTLY had the full 40mbps speed.
Now, two weeks ago I upgraded to the new option 2 78mbps contract because I wanted my P2P to be unlimited again, which they had stopped on the old contract. On day one I noticed that my IP profile was set to 52mbps and while i thought it was odd it wasn't set to 78 I thought I'd let it settle and see if it just needed time. For two days I got that full 52 down and about 12-15 up depending on time of day.
Then I had a power cut and when it all came back up my IP profile was set to 30.75mbps and I was only getting 30mbps up and 8-11 up depending on time of day. I rang up and they told me they would reset the line and profile. That was thursdaay, and today (sunday) its still showing my IP profile as 30.75 and I'm still getting the same speed.
When i rang again I got told that maybe that was all the speed I would get. To which I said how the hell could I suddenly be only able to get 30mbps when I've had no troulbe getting 40mbps on the old contract for well over a year.
Frankly this seems ridiculous, and made worse by the fact you have to speak to multiple help desks, none of which can actually do ANYTHING to help you, and anything to do with IP profile change or line reset needs an engineer to be sent out, AND he can't reset it either, but has to come out and then phone his help desk to do it.... CAN this system be anymore stupid?
I've been with BT since broadband first came out, but frankly the service has got utterly ridiculous, and this speed issue if I can't resolve it might be the final straw to break the camels back.
Sorry for the whine, but if someone can put anything positive to this I'd love it, as I'm very frustrated having spent many hours on phone over last two weeks since this started trying to resolve it.

Answer 1

in my experience I've never in all the years with BT seen the IP profile go UP automatically.  I can assure you that DLM profile and sync speed do go up of their own accord when line quality is consistently ok.  It does take much longer than you would hope, though.  Often 2 to 3 weeks, not even 'just' 10 days.
While waiting for a hoped for increase, it is worth disconnecting and reconnecting the router (NOT modem) each morning. Either use the web interface (I prefer that) or physically reset or power off/on the router.
The reason for this is  that the IP/BRAS profile is set for the sync speed (cabinet->modem) when the router makes a pppoe connection; the sync speed is set from the DLM profile.  The DLM change is always automatic, though often slow.  Sometimes, when DLM updates itself and forces a resync (usually in the middle of the night), the pppoe connection from router->exchange is also broken.  In that case, the router automatically makes a new pppoe connection and the IP/BRAS proifile is updated.  However, often the resync at the cabinet->modem level is so quick that the router->exchange connection carries on unbroken.  In that case you can end up with a fast new sync speed, but with the old slower IP/BRAS profile; this is fixed by manual router disconnect/reconnect.