A child that can not go almost 3-4 hours between bottles needs solids. That will stay in the system longer. The problem with the milk is that it is no longer satisfying so they need even more to keep the tummy full.

Barring that it may just be that the child doesn't know the difference between hunger pains and need to suck pains and you will need to just ignore the food demands if it is not time for the next feeding. The parents have taught the child that if I cry I get food. A soother just doesn't taste good.