unprofessional and broke confidentiality - Linux Systems Administrator OANDA Employee Review

I was looking to change my job about a year ago and I came across a job opportunity from Oanda. I sent out my resume to them waiting for an interview call. I should mention that my resume did NOT have any reference included. They did not call me after all and I ended up accepting a very good job offer from some other company. One week after I gave my notice to my manager, I had a chat with one of the seniors in my team. I found out that Oanda contacted my manager and told them that I was looking for job. It was a very unprofessional move and also breaking the law with employee's confidentiality. It also caused my manager to pass over me for an internal opportunity.I reached out to HR at Oanda in person cause it is a very serious deal to break someone's confidential information hoping that they take right course of actions to make sure that this never happens to someone else. The HR person seemed surprised at first and said she is gonna follow this up and keep me posed about the situation. But she did not bother to even shoot me an email after two weeks. Later, when I contacted her, she essentially told me that the person who had called my manager had "left" the company. This could be true but I find it very hard to believe given the circumstances.