There is no hot water in the shower.
DOC-cia — two syllables, stress on the first. 'cc' makes the 'ch' sound longer.
Report this immediately to reception. No hot water is a basic failure of service that must be corrected without delay.
'Non c'è' (there is not) uses 'esserci' in the negative. 'Acqua calda' = hot water (literally 'warm water'). 'Nella doccia' = in the shower. This is a fundamental complaint that Italian hotels take very seriously.
L'acqua è solo fredda.
The water is only cold.
Simpler statement of the same problem
L'acqua calda finisce dopo due minuti.
The hot water runs out after two minutes.
A common problem in older buildings with small water heaters
Il rubinetto del bagno gocciola.
The bathroom tap is dripping.
A less urgent but still reportable problem
Older Italian buildings often have small electric water heaters ('boiler') that need time to reheat after heavy use. Peak shower times (7–9am) can exhaust the hot water supply. Older hotels may ask you to call reception 15 minutes before showering so they can pre-heat the water.