Wow... 
This
thread is moving fast.
Ok, anyway I just checked the situation.
The fact
1. Having $1k phone bill is not Singnet error, the fact is you do
lost your SIM card and the calls were made directly through your
SIM account.
2. Since you report loss of SIM card after the calls were made,
they can't determined whether have you really made the calls.
3. The bill had already sent to you, with/without valid reason, you
are liable and must be responsible to your phone bill.
-------------------------------------------------------------------------
The
situation
- Police can only trace a person from making prank calls with their
phone number, and not the handset. Which means the caller is you,
and they can't further investigate due to limited evidence.
- MP will not meddle with cat and dog issues.
- Newspaper will report, yes, media sure has some influence power,
but after a fews days, this matter will be gone and you will still
have to bear your phone bill.
- Even the top 2 points is invalid, the police will not pay for
you, MP will presuade Singnet to dismiss your last bill, but
Singnet is not a charity organisation, if everyone has high phone
bill and complain to PM, people in Singnet will start to feed on
grass.
-------------------------------------------------------------------------
The solution
Take our helping hands. 
Look... you don't like money from others, but why still take so
much studies grant from the government?
Contradicting isn't it?
Anyway, it is only a small help from us...
Within our ability, help, otherwise, don't help.
So don't worry so much
