First thing they need to know ...
"DSG admitted they didn't have the know-how or ability to run a customer service call centre!"
The first priority of a call centre is to answer the phone promptly -- with a PERSON, not a machine. And to make sure that if a competent real person is not immediately available to take, they get the competent person to call back within half an hour and not put on hold.
Of course, with most companies the root problem is that there *IS* no competent person. For that, it makes no difference whether the person is in house or contracted, the customer will still not receive the deserved service.
It's worth investing in good people to deal with telephone problems because it does more than anything else to retain customer loyalty.