You tune to a movie channel on your British iptv. The film is English. The audio is German. You check settings. No option to change.
This is the audio language problem. Many British iptv reseller operators strip secondary audio tracks to save bandwidth. You get whatever language the source provider chose.
A professional IPTV reseller UK preserves multiple audio tracks. They know English speakers want English audio.
I once watched an entire movie on my British iptv with Russian audio and English subtitles. The subtitles were wrong too. I asked the reseller. He said "that's the source." No effort to fix.
What actually works is testing audio during trial. Pick an American movie on a UK channel. Is the audio English? Good. Is it something else? Your British iptv reseller has chosen bandwidth over quality.
In most cases, audio language is a choice. Resellers who choose to keep multiple tracks care about experience. Those who strip them care about saving money.
The pattern that keeps showing up: if they ignore audio, they ignore your experience. Move on.