Vodafone internet recharge 2G & 3G

I have also taken new vodafone prepaid connection no. 289. It got recharged after 24 hrs and that too by calling customer care 111) which itself is very stressful exercise. I stared using internet at night and suddenly got disconnected. On checking balance it show a negative balance of rs. 62. Next morning I recharged with 97 rs. With 2 gb internet. Again I topup it with rs 100 to make it positive of rs 20 approx. The internet recharge was come to work after 24 hrs. And that to after talking to customer care. I started using internet and after a couple of days I again recharged it with rs 97 of 2 gb plan.I started using internet and suddenly got disconnected. On checking balance it was negative 26 rs approx. I went to customer care at agra. They told me that it will take 24 hrs to make the 97 rs plan to work. I again recharged it with 50 rs there to make it positive of rs 15.75.But after 24 hrs the 97 rs plan still not working. I think I will have to again visit the customer care or talk to customer care to make it working. This time I also made calculations of internet usuage (calculations done on basis of 1mb = 1024 kb)and found that I ahve approx 74 mb left in my data limit than why it taken me to a negative balance in my core account. My main problems are that - 1. Why internet recharge is not instant in vodafone. Why it take more than 24 hrs to make it active 2. How to prevent minus balance. Why it goes negative. Why it DID not get disconnected after completely using the 2 gb which we got for rs. 97 recharge 3. Why we can't able to speak to customer care executive(no. 11). They keep on repeating the same options again and again. 4. What is the criteria of negative balance of vodafone. Sometime it is -62 and next time it is -26, etc. I also think that I have to stop vodafone and switch over to tata docomo instead.