Child support payments are mandated by court order, and thus they are the legal responsibility of the party ordered to pay. They are not based on either parent's desires or the interactions the two have with each other. These are debts that must be paid to give the child the best possible life.
Unfortunately, parents do not always pay their support on a timely basis — or at all. This is perhaps especially true in cases where the mother and father are no longer on good terms. This building resentment may make the person who was ordered to pay decide that they'd rather not do so.
When this happens, the parent who has primary custody may consider the steps they can take to force the payments to go through. If the other parent has visitation rights, the custodial parent may consider refusing visitation until the other parent is current on their payments.
This, however, is not the way to manage the situation. Visitation is a right — just like child support — that is outlined in the court order. As frustrating as it is to see the non-custodial parent breach that order, that does not give the other parent the right to do the same.
In short, they must allow the visitation to continue. They must not infringe on the other parent's rights or come between the parent and the child and keep them from seeing each other as often as the court determined they should.
So, what can you do if you find that the other parent refuses to pay and you need to take action? Don't withhold visitation. Make sure to look into your legal options.