Hi all.   I've lost a gate fob. Can anyone advise how I get another one?

Help! I need to isolate my incoming water but cannot see anywhere in the apartment how to do this. Advice would be much appreciated.  

Beautiful light beige chaise longue. Brand new, immaculate condition. 290cm x 150cm includes built in storage under arm rest, interchangeable. Pet free and smoke free home. We require a bigger sofa to suit larger family. Purchased for 1300 Euros, selling for 550 Euros