Do you even conduct quality checks on repairs as claimed?

I took my phone in for repairs on the 5th of July (cracked screen) , yesterday on the 15th of July I collected my phone from the Melrose Arch service center. After a tussle with with the poor service received from the agents, I got my phone 20 minutes later (waiting in line because only one person is permitted to go to the store room and that said person was busy). I then find out that when making calls people on the other end could not hear me, which wasn't the case before taking in the phone for repairs.

Claims of quality checks were made when I had enquired about the length of repairs as I felt it was taking too long to get repaired and now this? Is this quality check a sham because now I'll have to send the phone in for repairs again and be without a phone for another long period.

Next smartphone definitely not a Huawei.