BSNL
Oadband bill

Sir i have changed my bsnl broadband plan from home 250 to home 500 last month in august

My plan was changed on 3rd aug to home 500 and after that i am using home 500.

i have downloaded 60GB in August.

Now the problem is that they have charged me Rs 4000 for august month broadband usage.

what they have done is

60000MB/30days=that is 2000mb per day

now they have multiplied this per day usage with 3 (as my plan is changed from 4rd aug. and before that i was using home 250 plan)

2000x3= 6000 MB (they are treating this as Excess Usage)

now thay have charged me .80 Rs per mb on 6000mb

6000x.80= Rs 4800

now they have given me discount also and finally my bill is nearly Rs 4000

BSNL IS DOING CORRECT OR NOT.

PLEASE HELP ME WHAT TO DO.