Incorrect lenses & rude staff - stay away!!!

I got a new pair of glasses recently in June. They were okay when I tried them on in the shop but that week once I started using them I would get headaches and everything was blurry. I went back to specsavers and they said my prescription had changed! I don't think so the optician I saw said that was impossible so there must of been a mistake but specsavers still made me pay again to have them reglazed! I paid again and got my new reglazed glasses but they were all blurry this time and when I complained I was told to go away and try wearing them but it was clear I could not see at all when I got a test and couldn't see any of the letters but yet specsavers would not help. I told them I wanted a refund and was going elsewhere and then I was told I could not get a refund because I had worn them even though I had only being wearing them 5 minutes and hadn't left the shop. They then told me to leave the shop before they call security after I asked to speak to the manager!!! Stay away from specsavers!!!!