Getting a refund for a cancelled ITVX Premium subscription

I recently (2 weeks ago) took out a subscription on my iPad for the ITVX premium streaming service and paid for a year. I did this on the understanding that I’d also be able to use the same premium service across my other devices (iMac and LG Smart TV). However, I’ve now been told that because I bought this from my iPad, it comes under an iTunes subscription and I’d have to cancel it there but not necessarily get a refund. Does anyone know who to contact to put my case for a subscription refund for this streaming service?