Not happy with this product at all

I purchased a Zero gas stove from Lewis in Despatch last year.I told Lewis I did not like Defy brands because I have never ending problems with Defy. The lady at Lewis assured me this is a very good brand they had no complaints. I spoke to their sales person Lizzy last week Tuesday, she was going to phone me back. I had to phone the next day, then she told me her manager will contact me. no one phoned. I phoned this afternoon, I spoke to Ricky, the manager he was going to contact the supplier and get back to me. I even e-mailed ZERO Appliances last week to complain about the stove. no reply. We bought my daughter in law a Kelvinator. Once my gas was out, I used hers. I could not believe how fast her stove was. I cook an hour every night, with hers 10min and I was done. I was shocked. Lewis got Hal Fennell to connect an adaptor to the gas bottle. it was still slow. my daughter in law ran out of gas and used my stove it took her nearly 4 hours to bake a chicken in my oven. She told me this stove is a dudd. My mother in law came to visit from Jhb. When she cooked even she told me there is something wrong with this stove. We want to save electricity and cook fast. dissapointed