The fan club was mentioned on the sleeves of Marvin's 1981 hit singles "Marvin" and "Reasons To Be Miserable", as follows:
For further news of how bad life can be, write to:
The Marvin Depreciation Society, 2 Whitechurch Lane, London E1
The proprietors were:
SARM Productions Limited
London E1 6TD
The Marvin Depreciation Society seems to have died shortly after its creation. This is somehow appropriate.
The official Hitchhiker's Guide to the Galaxy Appreciation Society is ZZ9 Plural Z Alpha. It seems to have numerous addresses; visit their Web page for up-to-date contact details.