In app refund request being ignored

I purchased an app for my special needs child and an in app add on. However it wasn’t the right app for my child and very expensive. Apple refunded the main app £124.99 but has turned down and is now ignoring my request for refund of the in app purchase of £69.99!!! The in app add on is useless without the main app so I don’t understand why they turned down my refund request and now not even bothering to respond. Honestly I am so tired of Apple.