Waiting period is 28 weeks!!!!! more than half year

i booked Ertiga on February last week, even they marked 4 months waiting period, they promised to deliver the vehicle by May 2nd week , since then i have been constantly following up with the dealer and they keep on giving new dates every after 2 weeks. still they saw my vehicle has not boarded yet and have promised to deliver by July 3rd week. its been 5 months. 2 days back i got a letter from Maruti stating that, my waiting period has been renewed to 28 weeks, that is 6 months.