Complain

I got a message today from shein that my package is out for delivery, then I contacted buffalo couriers on WhatsApp to track my package, it then says my package is also out for delivery and I will will be delivered today ,few minutes ago i got a message that my package is being returned, REASON: TEL not answered, but to my surprise I have my phone in my hand but there wasn't a call or a message that says the delivery person is outside ,im so dissapointed