Well I've decided I'm just going to fix this myself - I'm going to dig a fair sized hole around the pipe and fill it with limestone chippings (a 25kg bag from
Wickes is £4), and cut the pipe at ground level so it sits right on the chippings. Then the condensate will always drain away, and there's not much chance of it ever freezing. I will also put an acrylic perspex sheet in the hole against the wall to prevent condensate coming into contact with it.
The way they've just done it is not very good because condensate will only drain into the earth very slowly (it actually takes ages), and thus back up the pipe all the way to the boiler. For this 32mm pipe, every 1 litre of condensate means 1.25 metres of back up, so the present arrangement will not work at all.