The Original Equipment (OE) Part number of the cabin filter factory-fitted to a Skoda Fabia Mk 4 is 2Q0819669.
A GOOGLE-search on 2Q0819669 should retrieve online adverts for the 'genuine' filter.
Or - when seeking online a (less expensive) filter made by a 3rd-party (Mann, Bosch, Ridex, Meyle, Mahle etc. etc.) - the OE number can be used as a guide to (hopefully!) ensure that a suitable filter will be delivered. Assuming that a 3rd-party filter looks visually OK, has the correct dimensions and fits snugly in a Fabia Mk 4's filter housing, I don't see how an owner can reliably assess its effectiveness or potential longevity.
It's to be expected that a Skoda dealership will wish to replace the cabin filter at the recommended change-interval and will use (and charge) for the 2Q0819669 part. As @Ootohere has said, unless the filter is dirty it is unlikely to affect the coldness of the temperature the car's air-con can reach. Worth checking the state of the filter (as it's easy enough with a Fabia Mk 4) but if it looks clean and has no debris in it, there's not much point in replacing it in the hope the air-con's performance will improve..
On my Fiat Ducato-based motorhome replacing the cabin filter was a thankless task needing removal/replacement of 16 screws, much cursing and sometimes blood loss. I used to replace the filter annually (with a Bosch filter) and, when the vehicle went in for service, tell the workshop manager that I had done this. As the Fiat mechanics used to hate the task, they were very happy to avoid it. I also fitted a K&N 'washable' engine air-filter that the Fiat mechanics did not need to replace. This (supposedly) increased the air-flow rate, though I never noticed any performance improvement.