Following on from the last post while I am still feeling particularly grouchy....
This doesn't work with clergy or bishops who don't answer letters, but when complaining to company, never write to the "complaints department", unless it is easily dealt with.
The best thing is aways to write to the chairman, ask him to ring you, or better ask him to let you come and see him, obviously a bit difficult if he is France! so you discuss your problem directly.
If that doesn't work get his home address from "Company's House" and suggest the next time you are in the area you could drop round and see him at home. It normally works.
Remember the Chairman's time is often worth 100 times that of the poor soul in the complaints department, even if he doesn't read the letter no-one in his office wants him bothered at home. If you can't find his home address you can normally find a club or an interest you share. It can be terribly annoying to turn up at Covent Garden to meet disgruntled of Dunsfold. If that happens he is going to be phone in the interval to his PA in the interval just to get you off his back.