How do you get apple to refund your money on a subscription you didn’t want when they refused to refund your money I feel like they just helped themselves to my bank account and took my money and then they made it impossible to get anything back

thi app popped up with a free trial so I thought why not so I downloaded it and tried it and when I saw that they were wanting almost 10 dollars a week for it I canceled it and then to be sure that it would not be billed to me I deleted the app and but then a couple days later I got an update my payment and I was billed for it but apple insists that I never cancelled the app but I did and now I am going to war with them because I don’t like being charged for something that I don’t want and then to add insult to injury they refuse to even give me an explanation as to why I am not eligible for a refund as for as I am not going to renew any of my subscription with apple including apple care plus because if I break my phone I definitely don’t want another one because of this