Fluid is not up to standard

I bought pure peach on the 10-11-2015.The agent at the desk filled up my twisp.I started smoking the twisp after I have left and discovered that it burns when inhaling and makes one cough.I returned to the store the next day as I was already out of the area.The lady at the counter said that she would keep the fluid and speak to her manager after she tested the fluid in her own device and had the exact same symptoms.Today on the 12-11-2015 I phoned and she advised that she would speak to her regional manager.After calling her the second time round about 16:00 she said that they will not replace the fluid as it has already been opened and used.The fluid is not up to standard so one would only know when you start to use the fluid that there is something wrong.