user: My partner booked a return flight, did not go on the outward journey and now can't check in on her flight back, plse help
agent: Hi Paul, sorry to hear this. Unfortunately, when you book a ticket with us you agree that your flights are taken 1/2 in sequence order. If not, then the remainder of your itinerary is cancelled out I'm afraid. 2/2
user: That's rubbish, she has paid for her flights. There was an emergency and she had to fly out earlier with a different carrier due to cost. Where in the small print does it say this?
agent: Hi Paul. We're sorry you remain unhappy. It's in the T &amp; C's on our website. You have to use the coupons in sequence and in the (1/3) order they're sold to you. If you fail to do so, then it will be registered as a no show and the return leg is automatically (2/3) We appreciate it's upsetting for your wife, but I'm afraid it's the rules on her ticket when she booked. (3/3)
user: Your rules not the rules and one doesn't know about your rules until something happens. Pay for something it's yours to use how you see fit
agent: Once a return ticket is sold, it must be used as a return, not a one way ticket, I'm afraid. We're sorry for your poor experience.

Customer is complaining about not being able to use the ticket for return journey. Agent states that it gets cancelled if the onward journey has not made.
### Instruction: Below is a conversation between a human and an AI agent. Write a summary of the conversation.

### Input:
user: My partner booked a return flight, did not go on the outward journey and now can't check in on her flight back, plse help
agent: Hi Paul, sorry to hear this. Unfortunately, when you book a ticket with us you agree that your flights are taken 1/2 in sequence order. If not, then the remainder of your itinerary is cancelled out I'm afraid. 2/2
user: That's rubbish, she has paid for her flights. There was an emergency and she had to fly out earlier with a different carrier due to cost. Where in the small print does it say this?
agent: Hi Paul. We're sorry you remain unhappy. It's in the T &amp; C's on our website. You have to use the coupons in sequence and in the (1/3) order they're sold to you. If you fail to do so, then it will be registered as a no show and the return leg is automatically (2/3) We appreciate it's upsetting for your wife, but I'm afraid it's the rules on her ticket when she booked. (3/3)
user: Your rules not the rules and one doesn't know about your rules until something happens. Pay for something it's yours to use how you see fit
agent: Once a return ticket is sold, it must be used as a return, not a one way ticket, I'm afraid. We're sorry for your poor experience.

### Response:
Customer is complaining about not being able to use the ticket for return journey. Agent states that it gets cancelled if the onward journey has not made.