If the agency denies service, ask for a copy of the policy or law upon which it is relying. If providers believe you will easily give up, there is a temptation to ignore you and focus attention on other families. Know when to compromise. In negotiations, both sides often must give up something. It is important to realize compromise is often necessary.
Flexibility is helpful.
Go up the chain of command. Sometimes a person with whom you are dealing is on your side, but lacks the authority to give you what you need. Understand this and be prepared to go to supervisors. Document your efforts. Letters that are short and to the point are helpful.