Worst service!

I am currently standing in the store after returning for the 3rd time. I simply bought a phone. Which was a terrible buy anyway because the battery basically lasted an hour (not even). Nevertheless, I wanted to return it. And yes fine, I did not have the slip but in today’s age if you can find the purchase it shouldn’t be a problem. After waiting for 30mins the first time they said they couldn’t find it. I had to come back. Then after another 20mins wait. They said I should go and they’ll email me with all the info. Then I am asked to return again because they cannot log into the phone! Why did they not ask me to do that from the start??!! I have now been standing here for another 20mins with no help offered! This is the worst service ever and I will never return.