As said dates, usage, class etc all count. If there in the same field likely confusion etc registered, unregistered rights hard without knowing name etc From a legal point most start with a “Trademark Infringement Cease and Desist Letter” (Plenty online) sent to infringer and Host (Most Uk, European, American (less so) will drop them like a lead balloon first whiff of anything remotely legal) If company is uk based ditto hosting etc makes it pretty easy as opposed to bongo bongo land with hosting in some dodgy backwater etc If your unsure then seek legal representation.