Can a debt collector charge interest on a leased vehicle that was repossessed in 12/2005, no payment since 09/2005 by us.

This was a leased vehicle that was repo'd in 12/05. The debt collector states they do not know when it was sold. They stated that they have begun charging interest in August 09 of this year, is this legal in the State of PA? Also they have not filed a judgement on us. - Is this your question? Add additional information