No CM Paid - Help Please

I have 3 children and the absent father walked out on us 5 years ago in the middle of the night taking all money and items of value and hasn't had contact with myself or his children since. The children are now 6, 11 & 12.
I originally survived on food parcels whilst the CSA chased him for 6 months after he refused to pay, in the end they placed him on a Direct Earnings Order.
When I had to transfer to Child Maintenance he was taken off the DEO and given the chance to pay by Direct Pay. I was very worried the absent parent would not pay Direct Pay, however, he did for a few months including the arrears which he still owed when the transfer took place.
A few weeks ago the bubble burst and he stopped paying. I notified CM and they tried to contact him via phone with no luck. They have now written to him.
The person who is dealing with my case at CM did say that if he continued to ignore them they could put him back on a DEO which although would mean I would be 4% worse off, at least I would be receiving some child maintenance.
My question is can CM go straight to a DEO or do they have to try the Collect and Pay route first. The person I spoke to at CM said that if they tried the Collect and Pay route, they would probably be wasting their time as if he isn't paying me, then he won't pay them. I'm not sure of the procedure of whether they can go straight for a DEO without trying the Collect and Pay first.
Any advice would be much appreciated. Thank you.