Typo error in sale deed

Hello,

I have a corner site in Bangalore with the below measurement.

East to west 30 feet

North to south 40 feet

However in the sale deed it is mentioned as below

East to west 40 feet

North to south 30 feet

The actual owner of the site is no more and the GPA holder is asking money to rectify the sale deed, all other document related to property (like Khata etc) are correct, can someone please advice how the sale deed can be corrected.

Thanks,

Ravi