this ageny is selling the cylinders in black

dear sir/madam
I am a resident of 450,dr. mukarji nagar delhi 110009,Everytime I book my LPG cylinder with ALOK GAS AGENCY shop no.1,c-14,model town,delhi 110009.
For the last two months I am booking my LPG cylinder but I am not receiving it.For your reference I booked my cylinder on 7th of march 2010 it is a computerised booking they have given me 87 no. It means my gas has been booked but I did'nt received that cylinder ,after 10 days I called them again ,they told me that you have not booked your cylinder as yet.but at the same time when I called the computerised booking ,the computer was saying that your gas cylinder has already been booked on 7th of march 2010 and you can only book your gas after 21 days.Then from some sources I got to know that they have sold my cylinder to someone else. Then after 21 days means on 30th march 2010 I booked my cylinder and got the booking no.184 but till date I have not received any cylinder from them.
This is a matter of trouble for us how can we manage without a cylinder.
Please take proper action against that ALOK GAS AGENCY if possible please cancell its agency.He is making fool of ordinary people.
waiting for your positive and prompt reply.
Thanks
Suresh kapoor