Speed cut to 8kB/s

I am a very heavy internet user (around 10GB per month without torrents) and since I am not settled I have been using Airtel's 3g services for the past few months. This month, out of the blue, my speed was reduced from around 250kB/s to 8kB/s Even though I had about 2GB of data left.
Obviously I called customer service to fix this and they said they will take care of it. The next day I got a mail saying that my problem has been fixed. I contacted them again and the same thing happened.
Finally they said that they have submitted a complaint to their technical team and would get back in 4-5 days. No reply after 1 week. I again contacted them. The jokers asked me to reboot the phone as there is no problem from their end. Obviously this didnt work, so they said they will get back in another 4-5 days. Again after a week, no reply. It has been close to 20 days since the original complaint and I believe they just want to wait for the validity of my 3g pack to get over.
Disgusted with Airtel, now I have got a photon+ and am thinking about doing MNP to docomo as the network is quite good around my area.
I have registered in the forum to specifically reply to this issue, and hope that it helps others.
I had the same problem around 2 months back and after fighting with customer care at Airtel I came to the conclusion that they didn't know what the whole issue was and how to resolve it. What has basically changed from last few months is that if I use more than 100mb in a day my speed gets cut down to 8kbps. To bring it back to regular 3G speed i have to recharge my account despite the fact that I had ample data balance in my account, and the real screw up is that airtel wont let you recharge your account if u have more than 50mb of data balance left. So I was stuck in a situation where i couldn't do anything and airtel customer care didn't understand anything. I escalated my complaint to as high as I cud (Regional Manager) and I always got the same reply that it wud be resolved in 48hrs. The audacity of the support people was that they would close my complaint without resolving it or even informing me. They wud just put in remarks that they spoke to the customer and all was OK. This happend not once but 3 times.
If u get a SMS saying that u have used 80% of your 3G data speed and a second one saying u have used 90% of data speed then beware u r very close to being downgraded to 8kbps.
Even as of today I don't have any solution to this problem, but since i can't live without the 3G internet what i am currently doing is recharging for 150MB at a go, it lasts for 5 days and is quiet close to the 1GB plan for 30 days in terms of money spent. Only problem is of recharging every 5 days 🙁
Update: I forgot to mention that when i had the problem for the first time it got resolved when my data balance expired at the end of the 30th day and it was not anything done by Airtel. So if anyone has such a problem then atleast u can expect to get back to normal speed at the end of your data plan and then be careful after that. BTW this whole thing is for a pre paid customer, I have no clue on post paid connections.