1) what is GP? please clarify .
2) builder has to execute sale deed in your favour . document has to be stamped and registered . then only will you have ownership of the plot .
3) mere affidavit or power of attorney is not sufficient .
4) if builder is dead deed of rectification can be executed by his legal heirs to correct survey no of your plot .
5) it is better to pay some money and obtain clear title to property
6) Govt cannot correct the survey number of your plot .
7) contact a local lawyer