However, she said that the indicator LED on the DSL adapter was blinking.
So I asked her how she had wired things together, and she said she had connected "the white box" to the wall socket. After a bit of asking, I found out that it was the NTBA -- the medium-sized box inside the parcel we had received from Hansenet, and the one that had a mains connection which we had never used at home. (Because it only needs power if you connect line-powered phones to it, but the only phone we hooked up to it had a wall wart of its own.)
So I told her we also needed the DSL splitter. ("But we didn't have that connected at home!" "Oh yes we did; I disconnected it this morning along with the rest of the equipment." "Oh.")
I explained to her how to connect the various boxes together and she said she'd give it a go. Very soon afterwards, she called me back and told me that the DSL adapter had only blinked a couple of times before settling on a solid colour. (Orange, meaning WLAN was off.) So that's good! It probably means that it synchronised with the DSLAM and that we now have DSL in the new house.
I'm planning on going over there this evening with a laptop to try it out and make sure that we do, indeed, have a connection (and not, say, just a DSL signal but no actual IP connectivity), but things are looking good. Whee!