The curtains are not working.
TEN-de — two syllables, stress on the first.
Report broken curtain rails or non-functioning blackout curtains, especially if street lighting or early dawn light affects your sleep.
'Tende' = curtains (feminine plural). 'Non funzionano' is the third person plural of 'funzionare'. Curtain problems can significantly affect sleep quality — blackout curtains ('tende oscuranti') that do not close properly let in significant light.
Le tende non si chiudono completamente.
The curtains do not close fully.
Specify the exact problem — they may slide on a broken rail
Le tende oscuranti non bloccano la luce.
The blackout curtains do not block the light.
Important in summer when it gets light very early in Italy
Il binario delle tende è rotto.
The curtain rail is broken.
Identify the structural fault
Italian summer mornings can be surprisingly bright very early — sunrise in Rome in June is at 5:30am and in Milan at 5:00am. Effective blackout curtains are essential for good sleep. Always check on arrival whether they close completely.