Sliver do have there own number to call in. Generally its much quicker than the standard line.

As for the delay, weather impacts it greatly.

Last Monday I called into the Silver line at 655PM CST to change my flight. I was given a message of 3 HRS and 16 Minutes and accepted a call back. Come 1030PM CST still no call back.

When calling again(1030PM) was told 4 HR 55 Minutes now but not prompted this time to have call back and instead placed in wait line for an agent. While on hold for 10 minutes made a last ditch to call my TA to see if they had quick in to Delta. During in trip progress they dont have access to $50 same day confirm change fee. My TA got through pretty quick.

Now the best part at 215AM Delta finally called me back from my 655PM Call back. It was awesome to get a wake up call 50 minutes before my alarm.