KFC DRIVE-THROUGH volume issues.

This isn't about food. I live next door to KFC Langenhoven Park in Bloemfontein. Their "Drive-Through" system is so loud that I can hear clearly what is said. They staff also "chat" to each other Via this PA system. I've been to the shop and complained. The technician came out and he adjusted the volume. This was good for about a month. Then the volume went up again. I spoke to a gentleman at H/O and I shortly thereafter received call from the "manageress", apologising and also asked me to call her directly. This I have attempted several times. I called their "customer" line, complained and was promised a case number within 4 working days. To date (after 4 weeks), still nothing. I called again and had the cheeky response by instructing me to take it up with the municipality. Today I tried to call H/O again but was diverted to a voicemail. I've had enough of the loud speaker for months now. No joy whatsoever. KFC Customer Service does NOT exist.