24/7 Electrical Services are dishonest and totally over charge

My tenant called in 24/7 Electrical Services as his earth leakage was tripping. They charged R600.00 call out which is acceptable but charged R3400.00 for 63 amp CBI earth leakage switch. Mass stores sell them.for R approx R960.00 and a small Electrical shop near me sells it for R850.00. My wife and I called them over 10 times and they keep saying they need to speak to the electrician who did the repair and they will call us back. They never have. I then called and asked for the owners name and number and they either tell me they will call me back and then put the phone down, in a meeting and will call me back, or will send me the number. In every instant, they just put the phone e down. My last call was the same answer that he will send me the number and when I said he can read it out to me, he just put the phone down. I subsequent called back over 15 times and they do not answer. While they repaired the problem (I hope), I believe they are dishonest ****** who overcharge. Unfortunately I was unaware of this call put as I would have refused to pay R4000.00 to change a faulty earth leakage.