"Helping witches and wizards find their marbles since 1426."
-- advertisement in the Daily Prophet (DP4)
The Mnemosyne Clinic advertises in the Daily Prophet that they perform charms to help fix up faulty memories (DP4)
No word on whether the Mnemosyne Clinic will help you forget things you'd rather not remember, or - alas - their location, though Diagon Alley is probably a fairly safe assumption (DP4)
Mnemosyne was the Greek goddess of memory and the mother of the nine Muses (Brewer's Dictionary of Phrase and Fable).
While the date printed on DP4 is 1 October 1999, the timeframe for these events is 1992-1993.