My ex isn't fit to take our son every fortnight because of drug addiction ! who do i call or see ?

Dont try to contemp the court orders, or u will be in trouble...Drugs and violent nature are the reasons for which u left him...but child belongs to him also, and he wont do any harm to the kid...but if u have, solid proofs showing cruelty towards the kid then produce it to Police or Court, u will get restraining orders...then ur kid will be safe...