Fixed REIN issue myself - now how do I stop the en...

Question

Hi
I (and my neighbours) have been suffering from slow (ie: 160k sync) or total loss of sync for a week.  We've all tried contacting our ISPs (BT for me), with varying degrees of success.  The whole saga of trying to get the point across that if it's six houses having the same problem at the same time, it's not going to be my router, and if upon changing my filter the line syncs at exactly the same rate as before, then "monitoring" the line for another 24 hours isn't going to achieve anything, etc, etc, is worthy of a 10-page rant in itself that I'll resist inflicting on you all.
Anyway - on my third call, finally talked to someone who eventually conceded it might be a REIN issue and booked an engineer (sorry, Broadband Boost) visit (although I almost got shunted down the further 48 hour "monitoring" period route).
Engineer visit is booked for between 8am-1pm tomorrow.
This evening, I happened to have the right combination of neighbours to do some investigations of our own, and sure enough, we have tracked down the problem to a single piece of electronic equipment in a house about 100 metres from my own.  The moment it was turned off, everyone's broadband jumped back into life, and I've gone from 160k sync back to my usual 1M (yes, it's blisteringly fast round here).
So problem solved - everyone happy.  Except I've still got an engineer visit booked for tomorrow morning.
I see the fault in MyBT, but there's no option to close it or to cancel the visit.  I've got a separate order number for the visit, but the order tracker says it can't track it.
I've tried calling the number on the confirmation e-mail (0800 800150) but I've been sat listening to the lady apologising for the delay for 40 minutes now, and there doesn't seem to be any hope of my call ever being answered - I suspect everyone's gone home (in which case I'd wish they'd say so).
So how on earth can I cancel the engineer visit?  What I don't want is the engineer turning up, declaring there's no fault, and BT deciding to bill me for the visit.
Any suggestions (other than getting the offending equipment turned back on again and letting the engineer find it for himself)?
Ta

Answer 1

So what's the "correct" (ie: as honest as possible but with no risk of getting a £129.99 bill) course of action now?
Do I ring and close the fault first thing tomorrow?  Do I explain to the engineer when he turns up?  Do I feign ignorance and express surprise the fault has "gone away"?  Do I go get my neighbour to turn the noisy kit back on again?