How important customers are to Samsung

On the 12th of November i took my Samsung Galaxy s9+ to the customer service station. The guy said that i had an LED burn and that the would have it fixed between 3-5 days. He also said they would send me a message / email. After 7 days of waiting with no sms or email about my phone i decide to phone the number on the service sheet. It took me two days including the technician taking lunch breaks at 4 in the afternoon to get in with the guy that worked on my phone. He didn't even pick up his own phone , i had to phone another employee twice to give him the phone. After all that he said that the phone had been fixed and should be at the store i took it to. So i went to the store the following day. Got my phone back and it was in exactly the same condition that it left. The guy at customer services said that they just did a software update. But the lines of the LED burn is still on my phone. He said that the technician probably did not see the lines on my screen. How on earth can you just send a phone back if the problem that was stated on the sheet was not fixed. I waited 7 days and if i hadn't called it might've been 14 days for the phone i sent in. No repairs no updates nothing. And just to add a very small crack appeared on my back glass. So what can i do about this