Sony Ericsson W20 — mobile handset not working properly

sir i bought a sony ericsson w20 on[protected] worth rs.7500. from then it has got 4 times problem.
near about in every two month l take it to the service centre .recently it had get reciever problem and slide problem. service centre repaired reciver prblem bt for sliding he said to left handset for 1 month. after feb the warranty will expire and if it again get problem then what i will do.
sir i m a student ,plz tell me what can i do of get out of rid of this problem.