Does not pay agreed overcharged amount back

SUMMARY:<br> Charge for work/parts not done/replaced and does not pay back after they agreed they have invoiced me incorrectly and will reimburse me.<br> <br> DETAIL:<br> Beginning of Nov 2015 Des Plumbers was called out to fix a leaking toilet at my tenant. After my tenant informed me that they only fixed it with silicon, I queried the amount I was charged at R1350 and the plumber who worked on the toilet who explained to me that he has to change various parts and that its a big mess, etc. No parts were changed. Only silicon were used. My tenant was watching the fix. <br> <br> I queried with Margaret from Des Plumbers who then got back to me confirming I was overcharged by R500 and asked if I would like them to keep it for future call out of pay me back. I still think the R850 was a way overcharge for fixing just with silicon but in any case I chose to pay me back but after several sms and emails I have still not been paid back. My last email was not even answered. I really do not know what to think. I have been using them for the last 8 years at 3 of my properties :-( <br> <br> <br>