Terrible service and no response

In February I contacted them to have my treadmill repaired. They came out (R600 callout fee) and informed me that the circuit board had to be replaced. I was told this would cost R2000. I agreed and they removed my circuit board, and came back 2 weeks later with a new one and an invoice for R2820. Once the circuit board had been replaced, I was told there was an issue with the motor and that they needed to file off a bump on it. They took my motor and came back a week later with a further invoice. Now when I try to use my treadmill, the belt jerks and struggles to move when i walk on it. It never had this problem before. I have tried to contact them several times to get them to come and sort out the problem, but emails get ignored and the phone rings and quickly goes to voicemail. I am extremely annoyed and just about ready to take legal action as I have spent a great deal of money, only to end up with further issues.