The UPC code mostly creates these issues. If you have a UPC from the G-one site, then open a case and provide all details, including the UPC code and G-one certificate. They will allow you to create a new listing under the brand. Brand registration only works if you register your brand in Amazon’s Brand Registry. If you’re already registered in Amazon’s Brand Registry, then it’s only a UPC issue.
Trade mark is easy to register in UK. Now a day Amazon now allow generic listing. Butt again if you just open case and explain with upc code and to submit G-one certificate of upc code it will help.