Quickpay - recurring payment without subscription !?

Could you guide me to what is the name of the language key that show the word "Delete" on the subscription pane on a profile? I need to add a parenthesis with "(Do not use! Use Unsubscribe)" - people do not understand the functionality, as I see here in this case.

There isn't a specific language string for that checkbox. Do not allow people to have access to those pages if they do not understand how to properly utilize them. Management access should be heavily restricted. A confirmation dialog warns you it is about to completely wipe the subscription from the database. You should be able to extend that message further using language overrides.

Have added a feature ticket to improve the delete behavior to check for recurring subscriptions and either cancel them or block the delete.

forge.joomlapolis.com/issues/8338

Ok - that sounds like a good improvement.
Now that the admin HAS deleted the subscription - is the only way to be shure that the user is not billed next year again, to delete the subscription at QuickPay too ?

QuickPay doesn't bill the subscription. The CBSubs internal scheduler does. First ensure the subscription is cancelled at QuickPay and if it isn't cancel it from there. Next in find the basket associated with the subscription _cbsubs_payment_baskets database table and set `scheduler_state` to 'C' and `scheduler_next_maturity` to empty datetime 0000-00-00 00:00:00. That should cancel the scheduler.

Ok - thank you. Have done that on this particular user and asked the admin to send a list with other users where he might have done the same.

I believe the best solution would be to block the Delete function until one has Unsubscribed the user.