For emails, all the tuesday emails during China working hours got a reply, we only have emails left from about 12 hours or so, so pratically no one gets a slower reply than 24 hours using sigma@sigma email.
Whatsapp we have a larger delay, I have replied to all whatsapps sent earlier than 48 hours ago. I also found some unreplied whatsapps due to some chat history deleted, only few ones and I took care of them. I also sent plenty of tracking numbers for the ones who request them.
BUT you need to know that if you send again a new whatsapp message actually it gets you on top in whatsapp, like if you sent a new message, so you are considered a 18th dec order.
And please stick to the ordering form, avoid useless chat to optimize the processing time.