Not refunding amount of Device.

Location/place: Bangaloru

Name of company/service: MTS

I Hemant Ghiya have purchased a MTS data card 700/- on 6/05/2012 from a vendor. His name is Chandru. He has told me if you are not happy with the service then they will refund all the amount which you have paid for the services. He also told that technical executive will come to your home he will give you access for the internet. Their technical executive never come to our home. Then we have any how started using the MTS services from may 18 but speed is very low in that. I have called customer care and ask for the speed they said that do this do that and cut the call. I have requested them to send technical executive my place but it has never been happened. I have pissed of with the MTS services. So I have asked them to deactivate my connection and send me total outstanding bill after deducting device amount. Now first thing is they have not send me total outstanding bill after deducting the amount of divice.
2. They are saying that they will not refund amount of device. When i have asked why they are blank. The data card is not useful for me in future and i will give back to them.
3. They are calling me and making me troubling mentally asking this and that and left and right.
4. They are not responding clearly some says we will reund amount and some says we will not.
5. They have sla (service level agreement) like they will give upto 3.1 gb downloading speed but you will not get this much speed a single moment. so I am totaly unsatisfied and furstrated with their sevices.So i need you to resolve my complain and refund my amount.