Changed BA travel paper tickets a few times in June. Each time BA did the change on computer. Last change was to fly LGW to AMS and not the already once changed LHR-AMS. BA agent at LHR Concorde desk did use one of those little authority stickers.
NOTE - if you do it via BA, they do NOT deduct the 2500 or 5000 penalty points. If you do it via QF even over the phone, they DO.
Note the pnr QF gives you is not the same as what BA uses.
------------------
~
Glen ~