If you have lost your keys, you are responsible for replacing any locks.
If you lose your keys, you must pay to replace the locks. An engineer can come to change the lock, but it will cost between £55 and £75 depending on the type of lock.
If you still have your key but the lock is broken, call the National Service Centre. They will send Amey or VIVO to fix it. If you cannot get in or out of your home, it will be treated as urgent.