Worse delivery service ever

Worst experience ever, I actually had to cancel my cellphone contract because of how bad their service was. First they state 12h00 till 16h00 then they arrive before the time and now they don't know where my cellphone is. Wow it's enough to cancel any dealings with them going forward and worst part is waiting over 20 minutes to call them and then they don't have the decency to call back.