Registration of flat

Hello Sirs,

Your inputs are very much required for me , So please help

Regarding FLAT Possession - Bangalore

I have purchased a FLAT in Jan 2010 with Posession in Dec 2010 doing a  "Agreement to Sell" with "Myself", "SBI Bank" and the "Builder", 

Builder is not giving possession yet, I had some payment late to him and for that he is charging me 3 L, Now the builder is saying he 

will waive of the amount if i give him the letter saying i have financial prbm as shown below.

"Dear Shankar,

You have to send us a letter saying you have financial problem, and then we can provide relief to you based on your financial problems.

However we would like to do your registration only after we have finished all items pertaining to your flat.

Kindly meet Mr.XXX and Mr.XXX in the site at the earliest, towards pendng works if any"

I heard from few local lawyers in Bangalore that if I give such letter to him, then he have rights to CANCEL the "Agreement to Sell" and 

sell it someone. I want to be sure before taking any step. Can you please confirm the same once again. Please dont misunderstand me. 

1. Should i send any letter like this?

2. Does builder has rights to CANCEL "Agrremnt to Sell" and sell it someone? is this true.? can builder do that?

3. My doubt is why builder is asking that letter.? What would he trying to acheive asking Letter from me?

4. How does the letter help him? Can he play any game?

My EMIs till date for 2 yrs are correct.

Please help and provide inputs

Shankar

sms1978@gmail.com