We moved into our house in August 2013 and had telephony issues from the off, with the line dropping (on ADSL) and poor voice quality and line dropping (on PSTN), with numerous calls to BT CS until the line finally(!) packed up altogether in November, leaving us without a telephone/broadband for 4 days until BT got it fixed. At best we were getting 1Mbps on ADSL as we were a long way from the exchange but the issues we had were down to a line fault. I eventually raised a complaint and requested compensation, which went unanswered. I was closing down my business over the winter and didn't have the time to deal with any more issues, so it was forgotten about.
We then found out that our local exchange had been upgraded to fibre and even better we could recieve it here and were enticed with the carrot of between 7-12 Mbps, which is when our problems multiplied. The line was installed at beginning of April and the engineer was "expecting a 16-20 Mbps connection", in line with others in our area, only to find we had 1.4 Mbps download....he went away and came back to say it was the best he could do and that we needed to raise this with BT CS. That we did and following a second engineer visit and then 2 weeks to get a survey (due to Easter holidays), we were finally told there was nothing they could do as we are too far away from our cabinet and the local (much nearer) cabinet is not available to us.
From having Infinity installed at beginning of April we've had nothing but issues with the service, dropping to 0.014Mbps at one point with a max of 1.8Mbps (average @1.4Mbps). For this we are paying £21.00 p/m for our BB, compared to the £16.00 p/m we were paying for the slightly slower but more reliable (post fix!) ADSL. When I raised this to BT CS I was redirected to the BT Options Team, who kindly offered to let us go back on our old tariff without penalty. However, as I stated to them, if we were stuck with a super-slow ADSL connection then I may aswell pay another ISP £1.20 p/m for the same capacity/speed package and asked if BT could do better, which they couldn't. I was also put though the BT Billing dept. who 'generously' offered us £10 for our troubles and then came back with a final offer of £15.99 when I laughed at them - the fibre package had already cost us more than that in extra fees (tariff + postage for router + days off work etc).
This renewed my resolve and I raised another complaint with the intention of raising a deadlock letter if it wasn't answered - we were then contacted by someone from BT who, rather than trying to passify us, was standoffish. He offered us a 'best' offer contract of £13.99 p/m for ADSL and said it was better than the other ISP deals as it was "truly unlimited" to which I suggested we could only use at most 20GB per month given our network speed! Alas, the joke was lost and he asked for an immediate answer, even though I stated I'd speak with my wife before making a decision on whether to stay with BT or not. I was then given the hard sell treatment and 'told' that he assumed I was the decision maker and he wanted an answer now as otherwise the offer would be withdrawn. I then said if we agreed to the new contract what would BT do to manage my compensation claim, to which he said "this ends now", meaning he was bribing me and I needed to go away quietly if I was to get any resolution at all.
Even though I've had my BT webmail account (Talk21) for donkeys years and many of my third party websites are linked to it, even though I like MotoGP and therefore benefit from BT Sport, the truth is I'd be much happier paying £1.20 p/m for a crappy service than £13.99 p/m for an equally crappy service and feel I've been palmed off.
Unfortunately BT is proving it can't maintain it's reputation for high QoS whilst competing with low cost (low overhead) ISP's who can offer almost the same service for less than a 10th of the price of the UK's biggest supplier. It also seems BT's 'no option' value add's (BT Sport, webmail etc.) are making for some very unhappy old and new customers as it's pricing them out of the market.
We are now awaiting the deadlock letter, which I'm pretty sure will not improve our situation as BT no longer cares.