Lufthansa extended my miles and status but I pulled a stunt to do so. I rang them with 10 travel destinations and a range of dates for each, in economy and business classes, and none were available (of course I'd been sly and checked beforehand). So I said I felt I had a good case for extending the validity of my miles.
The lady had a sense of humour because she said : "You know ve are Cherman and venn ze Chermans make ze rules it is a serious matter. But I vill see vot ve can do."
Well, two weeks later I got a letter extending my miles! You could have knocked me down with a Messerschmitt!