Airtel 3g dongle gives worst internet speed when in 2g mode

I have a airtel 3g dongle (no: 05), on which I got 2gb limited data plan in 3g speed then later plan changes to 2g speed. But what I found is; while having 2g speed, the net access is totally slow, dead slow. Its of no use browsing with this data speed, I cant open my yahoomail box, even the google search also. Even a net access via my cell is double the faster as this. As I checked the 2g speed in dongle I see the speed is not showing more than 15 kpbs, and often it goes down to 0 kpbs, now u can guess the upload speed, its null. Websites are showing 'no response'. And I am wasting my time. While calling to the airtel customer care, I was told to be happy with what I have and wait until the billing period, where I will have my 2gb credited. This is not at all a satisfactory approach!!!! please look into this issue. It would be good to change the strategy which is being implemented currently, in this age, where 4 g speed is being popular, please maintain some standards and don't let your brand name go down. Here, very often I am seeing people complaining about way internet speed is distributed. I never expected this much bad speed in a airtel 3g dongle.