Nokia — Suplly of Bad Hand set

I bought a new Nokia E71 on 18th January from Mobile Store Sahara Ganj,, and realize that phone gets hang atleat 10 times a day, I visited Nokia care center at Alambagh Lucknow and they update the software on 27th Jan.The problem was same on the next day and so Center people asked me to submit the phone and they will forward it to Noida for repair on 28th Jan. Yesterday i.e 9th Febuary I got back my phone and realize that the problem is still there. Now I contacted Mr Sumit Tripathi who manages UP East and as per him I have to again submit my phone. When i requested him to replace my phone, he misbehaved and shouted on me stating "How can you expect your phone to be replace" because I have submitted only once for the repair, he said as per Nokia policy if your phone doest function properly after 3 times of submission for repair, than in that case you will get a replacement. I have spend Rs 16000 on Business Nokia E71 phone for myself to use but out of which only 6 days this phone was with me. Again they want me to submit my phone for 10-15 days to get it repair and are not ready to give me written assurance that it will be fixed this time. Still they are not giving any assurance of replacing a bad hand set they have given to me. My Rs 16000 have gone in vain, Nokia is cheating with its customers.