I have a 22 week old puppy she is a chi cross jack russell she is driving me made she is pooing and pee all over my house even though she has a dog flap she wiill pee right in front of me and poo she knows what she has done so please can you help me and my 4 children thank you

Do you have a routine set up for taking her out for potty breaks?

I would ignore the fact that you have a doggy door for now and physically take her outside after every meal and every time she wakes up from a nap. You may have to wait outside with her for quite a while until she goes but when she finally does praise her like crazy, make her think that weeing outside is the best thing ever.

When she wees inside if you catch her you can give her a gruff "uh-uh" but other than that just clean it up and go about your business. I have found that my dogs respond much better to positive than negative reinforcement.

Next thing to ask is how confident is she in using the doggy door... Does she seem apprehensive about it at all?