inadequate speed and occasional absence of the internet access

Location/place: Ahmedabad

Name of company/service: Spidigo internet

i had activated a night zoom plan of spidigo internet 4-5 months ago with upto 512 kb/s day time and upto 2 mb/s speed at night. but all the time either i m unable to connect or there is inadequate speed…so it is such a waste of a time to keep on waiting for speed even though the payment of the plan is done correctly…they record the complain, send therir engineer to correct the problem and within few mins,,, it is the same…no speed, or no access…kindly do something