Bad after sales service

One of my staff members Mr Elias Khumalo purchased a LG HiFi in Dec 13 (with an extended warranty). It started to have sound/volume issues so was returned to be fixed in Dec 14. This took 3 months and on return, the same problem persisted. I called Mohammed at this time in an effort to get it fixed timeously and properly. He assured me it would be ready last Thursday and that he would call me to confirm (which he didn't). It was however ready on Monday, only to present the same sound/volume problem. This is not only frustrating to the owners but costly to go up and down trying to get it sorted out. JD has kindly agreed to collect the amplifier (which seems to be the problem) today or tomorrow. Hoping that the fixing thereof can be fast tracked and correctly done this time?