charges for non use

Location/place: belgaum

Name of company/service: vodafone

Dear sir/madam

i have bought vodafone 3 g dongle post paid plan 850 per month firt off all there is no proper service , no speed as per 3 g paln only 50 kbbs and they charged extra charge 1200 as usage charges and deactivated intert and charging bill for non use of internet