When in such a situation, don't be argumentative. You are as likely to change the other person's opinion as you are likely to want them to change your opinion. Just keep that in mind at all times!
What does help, is you showing an interested and grateful attitude (in fact, exactly the attitude that you seem to have been hoping to have received from the people you were speaking with, but sadly, you didn't find).
By all means, gather neutral evidence (date, time, place, names, decisions, actions) and do so in writing. But most importantly, be good at what you do - if you like people, then be supportive of their attitude to life, if you like work, then be supportive of their attitude to their job, if you like their work environment, then be supportive of their conditions, and if you like being argumentative and confrontational, then wind them up with arcane industry conditions and guidance.
As I read your request, the combination of tickets is valid, but most duty personnel will be unable to verify it, and most will err on the side of caution - refusing it.
Any challenge during travel can be taken up with senior staff later, and they will be able to resolve the problem for you. Please let me know if you need any assistance with that.