On the understanding that there is no problem with the plumbing supply reaching your Mira Supreme, the symptom you have reported is almost certainly due to a failure of the Solenoid Valve Assembly. However, please appreciate this is conjecture as we cannot guarantee accurately diagnosing a fault without the benefit of inspecting a shower. Having said that, and as confirmed by Selina, the Mira Supreme is a product we no longer support in the field so we are unable to arrange for a Mira Service Engineer to visit site to investigate the matter.
The Solenoid Valve Assembly (part number: 817.06) is one of the few spares still available for the Mira Supreme, and it can be purchased from us presently for a total cost of £39.33 (inc. delivery and VAT).
Mira Engineer, April 2009
