Netflix complaint: Second Account

Hi there
After noticing today, I had been charged for a second account with Netflix.
I contacted customer service. Only to be blamed for the problem myself. The man said I’d changed my details but never contacted them.
Saying that it was my fault someone had used my details and charged my account for there premium services which is double my own subscription. So instead of having my own bill I was charged 10 times 15.99. Even though netflix could see the other persons name and location. I was never notified.
I have checked through dozens of emails to see if I had changed my password at the time of first charge. No such change took part and my details were either giving or taking from Netflix.

The man if I may so, didn’t care suggesting I should of notified them when making changes as if it was fact. Even tho I have no email suggesting I was charged for a new or second account.