Mira Showers Faults Why Would A Shower Cut Off After Just A Few Minutes?

Why would a shower cut off after just a few minutes? - mira showers faults

We have a Mira electric shower, that I bought from B & Q and is only 4 months old.
The problem is, only a few minutes after cutting. The light in the tire and the shower itself remains in the water, but flow perfectly still.
It began yesterday, after my wife, the temperature display and minutes later .... he continued.
My dilemma is this .... is an error in the shower, the power supply, or something else?
Is this a problem with the device and take on B & Q, which would probably then pay again for installation .... That would be unfair, or if you fix this?
I would appreciate advice from people who know, please.
Thank you!