@Mariam16 This is not live chat, it's a community that is manned mainly be fellow customers, if your sim is not working then check the service status for any issues in your area https://www.sky.com/help/articles/service-status-Sky-Mobile if that doesn't show any issues you will have to find a way of calling sky to request a replacement(you could also try Sky's social media accounts for help).
@saffia11 Live chat does work, it is however quite popular so it's hard to get connected, it's just a case of keep trying.
