Poor service

Handed Sony amplifier with serial no. 6622105 to Rocket Industries on 7 September 2020 for repair. I paid a collection fee and deposit of R380.00. I collected the unit at their premises in Moreleta Park on 27 October as repaired and working and pay another R200.00. The amplifier was in the same condition as handed in during September and not working. I phoned the company the same day and complained about it. Rocket Industries collected the amplifier again on 26 November 2020. After numerous phone calls and excuses I went and collect the unit at their premises on 15 January 2021. The lady then promised to refund the R580.00 as the amplifier has not been repaired. It is the 8th February and no refund up to date. Every time I contact them I receive another promise of immediate payment. After six month the problem should have been solved by now.