Off topic but given the importance of repositioning flights and often associated hotel bookings thought I would share a recent experience.
I booked a flight with an Opodo Prime discount and the standard 30 day free membership. Obviously this auto renews for something like £60/year so needs to be carefully managed. When I phoned up to cancel they initially offered me £4.99 renewal on rejecting that I was offered £4.99 renewal plus £70 off any flights over £71 and £100 off any flight/hotel booking over £101. Flight voucher easily used and flight/hotel 1 night with a throwaway low cost return effectively got me the Ibis Styles Budapest Airport Hotel for £15. Cannot vouch for their customer service and obviously need to go through the cancellation again next year but has worked out well so far.