Sorry to hear this. I have copied a couple of articles that might offer you the help you need. I'll have my fingers crossed for you that it works.
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Tip No.8 Obey

Your dog should obey any command that you give him

within two or three seconds, if he does not obey you then

he is either ignoring you, which means that your position as

alpha dog is under threat, or he does not understand what

the command means and requires further training.

If he responds to your command in some situations and not

others then it is likely that he is plain ignoring you when he

does not respond. To prevent this from happening use the

"Alarm-No-Command" method. This method has three

steps that you take when your dog does not respond as you

wish.

1. Use something to alarm your dog, such as a squirt from a water pistol or

shaking a pebble filled can. Make sure that you do this while he is in the

act of misbehaving or ignoring you.

2. At the same time say a loud "No!" or "Bad" or utter a sharp growling sound

like "Aaahhh". Use a stern voice so that the dog recognizes the difference

in tone from your normal voice. It is important that the voice correction is

sincere and that the delivery is consistent so that the dog associates the

harsh word or words with stopping the behavior.

3. Then redirect your dog with the command.

Remember from SitStayFetch that when you issue a command it is helpful to be

in a position to make sure that your dog physically does what you ask.