ielts for australia

I took the IELTS twice because of the writing part only. The first time, all my scores were 7 EXCEPT writing which was 6.5. I thought I would blame it all for not having the time to concentrate in the review for the IELTS. Then I took it again, but this time I went on leave in the school where I taught Nursing subjects and I did forego the salary loss and the amount of the review for the IELTS....
I did the IELTS and got Reading 7.5, listening, 7.5, speaking 8 ...yes...very well done now..but..my WRITING score was still 6.5

Can't do any more..too frustrating...well not my loss really..if Australia cannot have me as their citizen, I am not only a good nurse , I excel in almost anything I would do..plan programs, develop trainings, give outputs and establish hospital camaraderie thereby cheerfully lighting up hospitals which may be boring...
My score is truly accepted in Canada and in the U.S. though...not to worry. hahaha Optimistic still..

If ever I took the IELTS again. Does it mean that my latest result is the valid one. Can I use the previous result? or it was already invalid?