Ignoring a customers plea for customer service for disabled child’s app purchase

I purchased a disability software communication app for my autistic sons iPad (so he can have a method of communication) through apple store, $229, using Ndis funds. The method of purchase was the most confusing app to download (like nothing I’ve experienced before) and after it glitch on the initial transaction, I bought the wrong item in error. I tried to exchange for the correct software (same price). Apple refused point blank. Develop said it was fine buy them. I disputed the transaction with my financial institution (so I could afford the correct one) and wrote a long heart felt explanation. Apple ignored all efforts of communication and barred my credit card for all future purchases, regardless of all the $1000s I’ve spent in the past with no explanation . Ironic that apple sells software products to empower disabled non verbal individuals, but at the same time takes advantage of their ability to have their advocate ignored and to preclude a disabled future subscriptions & purchases. Very disappointing experience. So how do I fix this is ?

Regards Natasha Bonasera