Bad service

Good day

I bought an iPhone 6 online in April when it arrived we set up it manually and Apple ID and password was never created. The phone immediately after it locked itself showed it must be connected to iTunes. I took the phone to Nelspruit branch, they said l must turn off the “find my iPhone” off which l didn’t turn it on and l don’t have credentials to do it. The phone is currently with me with an Apple ID that l don’t know and no hope of it fixed. I’m very dissatisfied and want to return it.