BOI repeatedly flagging genuine Apple subscriptions

I appreciate that BOI has greatly increased securing measures, and indeed I had a dodgy (useless) adware account that got downloaded on my PC flagged and payment stopped, but I’ve been trying to make totally genuine subscriptions through my iPhone via the Apple App Store, and repeatedly they fail and I will get a message or phone call from BOI re suspicious activity. It’s becoming a bit tiresome at this stage. Mostly Apple subscriptions are genuine transactions. Having messages come up that server keeps denying them has just got very annoying.