Join Date: May 2012
Location: Munich, Algarve, Sussex or S.F Bay Area
Programs: Mucci, BA Gold, A3*Gold, LH SEN, HH Gold, Marriott Plat, IHG Plat Amb
Posts: 5,594
Depending on your ticket, IAD-LHR-CDG may well be cheaper than your current IAD-LHR ticket, subject to booking conditions and fare class. In that case the advice from ianwall is good to cancel to a voucher and use the voucher for the new booking. Any residual amount remains on the voucher.