Problems with Homepod - ask "Hey Siri, Play Capital" but get other stations, currently Capital Extra

We have a Homepod which occassionally struggles when we ask it to "Play Capital", which should just start playing Capital FM radio. However, on occassions, when you ask it to "Play Capital" it starts playing Capital London, or Capital Extra - which can be requested by saying their full name "Play Capital London" or "Play Capital Extra" but even when asking that, it seems to get stuck on whichever station it decides to play. The only way I can change it, is by playing Capital through my phone and then airplaying it to the Homepod. Frustrating when something so simple messes up - any suggestions on fixes or saving a specific radio station to Siri's memory to play as a favourite?