When you go to that link does it basically say that site is only for US models? Since you’re outside the US, can you just google “2014 civic radio code” and see if there is an international Honda site or info on how to obtain it? It could be on the side of the glovebox, or with paperwork...
https://crmshonda.my.salesforce-sites.com/service/hondaw2c
I’d also connect with Honda corporate to express what’s happened with your dealership experience, because 30k miles isn’t old, and they’re just trying to sell you a car instead of fixing yours.
Are there any other dealerships besides that one that are within a decent driving distance? Sounds like that dealer is an absolute joke. The car isn’t going to just become slow because they said it’s “old”. 30k miles is not “old”. They just want to sell you a new car. You need to find...
Do you have a Honda dealership near you? It would be worth taking it to their service dept and have a tech drive it with you to see what you’re experiencing with the throttle response. Was it a Honda dealer that did the clutch and looked at it before, or was it just a regular mechanic shop?
when you try to activate the econ mode button, do you see the change on your dash showing you're "in" or "not in" eco mode?
it should have some type of green leaf icon, or maybe it says econ on your model?