I understand that you wanted to know why you still cannot sell in Amazon UK, and wanted to know if the policy warning that you received is the reason why your account is suspended. Upon checking here, I can see that your account is still under pending validation. That is the reason why your listings are still not showing on the website. The policy warning that you received is not the reason why your account is suspended. That policy warning is just to notify you about the infringement complain from another third party seller, and they notify you that they removed your listings for the product.
They advised you to provide a written approval of the Third Party named below; or an original invoice of the source of this product. You may also contact the Third Party with the following contact details:
In addition, regarding the verification of your seller account, please confirm when you completed all the required documents, or when did you submitted the last document to proceed in the validation of your account.
I apologise for any inconvenience this process might have caused you.