Is MG warranty a sham?

[Joonee]

I contacted the MG Aftersales Customer Experience Centre to determine if a battery issue was under warranty. They replied - the car undergoes an investigation by the technician and the results go to the warranty team who then come back to the dealership and advise whether the fault would or would not be covered.
Why won't they define what the warranty covers and what is not covered. There is no value in a warranty which is totally under their control and authority. To add insult to injury there may be an initial diagnostic charge of £140.00