AMENDMENT No. 1 and WAIVER No. 1 TO THE CREDIT AGREEMENT dated as of April 7, 2006 among Kansas City Southern de México, S.A. de C.V. (formerly known as TFM, S.A. de C.V.), as Borrower ARRENDADORA TFM, S.A. de C.V., as Guarantor CERTAIN LENDERS, BANK...