Scenario:
I made a call to a call center, but I didn't receive proper reply; hence, I again called the call center. Executive there picked up my phone. My conversation went like this:
My name is XYZ. I called your executive sometime back and discussed my problem but he didn't give me satisfactory solution. Hence I called you again.
Or Should I Say.
My name is XYZ. I had called your executive sometime back and discussed my problem but he didn't give me satisfactory solution. Hence I called you again.
Which conversation of mine is correct?
Should I use past perfect or simple past? Why?
Please explain me uses of simple past and past perfect