Very bad products and services!

I never expected a drop of 0.6% in my earning interest rate which I get in my ANZ advance notice term deposit. I am a customer of ANZ bank, and when I bought this account, I was guaranteed a fixed 1.60% p.a. for 8 months, after that, the expected return on investment was said to be 1.3%, but it dropped to a surprisingly low of 9.98%. I was very shocked. When I called out to my customer service; even though friendly, they were unable to resolve my issue. I demanded an explanation but noting concluded. Then a month later, this issue was finally resolved and my interest rate retreated to 1.3%. But this was a grave inconvenience for me. The customer service needs to improve.