TD-W8970B and TD-W8970B are two different products...cannot upgrade from one to another.
Why do you want to upgrade it? Any problems there?

actually i purchased tplink td-w8970B ....but it comes with frimware of tplink td-w8970

source link of product i purchased : http://www.tp-link.com/en/products/details/cat-15_TD-W8970B.html

source link of product whose frimware i got in my product : http://www.tp-link.com/en/products/details/cat-15_TD-W8970.html

actually i purchased tplink td-w8970B ....but it comes with frimware of tplink td-w8970

source link of product i purchased : http://www.tp-link.com/en/products/d...TD-W8970B.html

source link of product whose frimware i got in my product : http://www.tp-link.com/en/products/d..._TD-W8970.html

That's weird.
On devices itself, the model is W8970B, while it shows W8970 on its web interface?
Can you provide the photo and screenshot?
Is it a brand new device or a secondhand one?

actuallly yesterday i gave the device to serveice center and they told me to wait two days
today they call me and said to sent email about this problem to [EMAIL="support@tp-link.com"]support@tp-link.com[/EMAIL]
and wait for their reply
the person who called me ...said that the td-w8970B is not available for india only td-w8970 is awaliable
i am soo much confused and tensed right now ! ....thinking what gonna happen? ,will they replace it or not ...?

If the service center refused to replace it, you should contact the shop where you bought it as it is their fault.

i told seller for refund or replace but they are not willing to do it , they are saying { contact service center ...its there issue ,its not use in contacting us }

I bought the same model and the same thing happens. Did you manage to fix it?

not yet bro .... still no response from service center , look like i lost my money
what about u ,do u manage to get any response from them