No response no feedback

So i bought this groupon to have my car serviced at Cambridge motors in Town... long story short the company which i took my car to was a big rip-off, they charged me an extra R1500 above my groupon purchase and they never even changed the oil in my car... nothing was done to my car, the so called invoice didnt even have a cost for the items they replaced just a total at the bottom not even VAT included.. WTH! anyway my complaint is directed at groupon because i informed them of this situation and I received and email from Jehaan who asked me to elaborate, which i did and would get back to me between 3-5 days. after 8 days i sent an email to Jehaan asking for feedback and no response was received.. its been a month later and still nothing.