Huel, this is why your subscription-updating UI needs to make it absolutely crystal clear what is happening. Here’s a good principle to abide by: any time a merchant takes money from a customer, it must be clear that this is what the customer explicitly intended. The intention can be expressed in various ways, such as confirming to it in a very clear UI, or saying so in person, or whatever else. But the intent must be there, in the user’s mind. The current subscription UI fails this criterion.
Do not penalize users, especially not financially, for your UI inadequacy.
Here’s another example of the subscription UI being unclear: Setting a subscription shipment date to today's date
Imagine you text a human with a request saying “please change my next subscription date to [xyz]” and they text back saying “k”. Or you make this request in person and they make a vague acknowledging grunt while continuing to play Candy Crush on their phone. Seems rude doesn’t it? You don’t really know whether they’ve understood your request, how they’ve interpreted it, whether it’ll work as you intended, etc. That’s what the website is like today.