You need a stop button for what? Stopping your subscription? Of stopping something else?

If you want to close your subscription, you can close this in the webplayer or in the app.

Go to the settings and there you are able to close your subscription.

In and for a refund, you’ll have to go to:

https://support.deezer.com/hc/en-gb

You can submit a request about your refund.

They should provide information on how to get in touch with their customer support team, either through email, a contact form, or live chat. Explain your issue regarding the lack of a stop button and request a refund if applicable. Their support team will be able to guide you through the necessary steps and assist you accordingly, It's important to note that each company may have its own refund policy, so make sure to review the terms and conditions or refund policy provided by Deezer to understand the options available to you.