When it is too costly for BT to fix, maybe?
Having a fun one with BT (well, "fun" is not the word) where an unfortunate customer has lost just over 25% of the 63Mb/s speed they had on FTTC when their neighbour also got FTTC.
It is right on the borderline, but (we think) the wrong side (for BT) in that it did drop just more than 25%. Not many people realise that an FTTC line should not drop by 25% over a 14 day period. It is there in the handbook, but even BT do not seem to understand this. All they seem to care about is that the availability checker shows the estimated speed which matches what the line gets (well, it does now, as it seems that they changed the checker!).
BT seem totally happy to ignore their own rules if they are not convenient. What is worse is they know the cause of the problem (a short length of Aluminium cable) and the fix (to replace it with Copper), but that is not something they want to do - even though they are the ones that made this 25% drop rule.
We'll see how it goes - if they actually agree it has dropped more than 25% but still refuse to fix the fault, then this will be more of a story. I'll post more when we get to the bottom of it.
From our point of view we don't guarantee any speed, so whilst we are not in breach of contract with our customer, and we charge the same for 46M as we do for 63M, it is not exactly very nice on the customer to lose the speed like this. As a result we are doing everything possible to try and force BT to follow their own rules and fix the problem.
Update: Unfortunately, analysis of the sync rates and changes suggests that for this customer the sync rate dropped just too slowly. i.e. more than 25% overall, but over more slightly than 14 days. The rate drop within 14 days being just below 25%. Asa result BT have refused to take any action to restore the previous speeds. In the long term vectoring may provide a means to reduce the crosstalk affecting this customer, but this could be some time off.