Generally I lurk, rather than post, but we followed the recommendations on this thread for Alfredo from Alfgaia and they were brilliant. He and Terry have cleared the wilderness from the back of our garden, which was a massive job! (On reflection, we probably shouldn't have just left it when we moved in 18 months ago...) They also pressure washed our drive and patio and it honestly looks like it's a brand new one. Would definitely recommend them, and will be getting them back in to do some more work in the future.
Now we just need to work out what we're doing with the former wilderness so it doesn't revert to that state!