Subscription Reactivation Does Not Work

While cancelling a subscription works (please make it more user-friendly, not hiding it behind the three dots in the account!), the reactivation does not. When I try to reactivate a subscription, the price is 0, but the tax is calculated. The user just pays the tax and received a payment pending for the rest of the price (the net price).

Also, is there an option to let the user cancel by the end of the current billing cycle? My users can cancel anytime, but I do not refund for the unused time. They can use the membership until the end of their current billing cycle.