On 13/04/2012 11:52, Roland Perry wrote:
It doesn't even make sense for it to be "within two weeks of the end of
the 8 weeks", unless they are secretly keeping everything for 10 weeks
so they can sort problems out.

It doesn't make much sense. Here is their reply to my query:

quote
Oyster card journey history is held for a period of eight weeks. After
eight weeks, the information is removed from the Oyster card and kept
only for statistical analysis. It is not possible to reconnect the card
and the journey history. Regrettably I’m unable to investigate further
any overcharge which occurred on or before February 2012 as this is
beyond the eight week period Transport for London (TfL) can hold journey
data pertaining to individual customers’ accounts. The eight week period
was felt sufficient for our needs whilst not infringing on customers’
rights of privacy and complies with the Data Protection Act 1998.

Our Conditions of Carriage state that, any claims of this nature must be
contested within 14 days of the journey in order for a refund to be
considered. To download a copy of our Conditions of Carriage please
visit:
http://www.tfl.gov.uk/assets/downloa...nuary-2012.pdf
/quote

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Clive Page