I logged into your site, but I was registered before with a demo site only, and I completed the purchase process, but I do not want to use the demo site. I want to use this site. If there are difficulties, the amount can be returned and I will buy again.
Cloudflare doesn’t offer refunds, as per Terms of Service 4.3
However, you can certainly ask for a credit you can apply to the correct domain. Open a billing ticket and explain your situation.
To contact Cloudflare Customer Support, login & go to https://dash.cloudflare.com/?account=support and select get more help. If you receive an automatic response that does not help you, please reply and indicate you need more help.