Can you give an example of such a warranty? Any I've seen clearly call out that the warranty is in addition to your statutory rights. I'd genuinely be interested in reading the history of the case law you refer to also, if you're familiar with cases, it should be easy enough find them in the online search tool.
I'm advocating reality, your contract under which consumer protection is enshrined in law is with the vendor, not the manufacturer. Any warranty or after-sales service a manufacturer chooses to offer is done so out of good will and brand reputation protection, there is no obligation under law for them to do so. Also, charging port failures are 99.99% the result of abuse, and that's very obvious as soon as you open the device. Such abuse is not covered by statutory rights.