Sir waiting in lines is not an issue, i do this, my dad did this his entire life, and i never pay a single rupee extra to get undeserved favor.
What i am talking about is when a car has some issue, then one has to deal with it this way, there is no other way (other than the officer is your friend). My dad has a friend who has close links in the excise office therefore he never paid anything extra. Even i didn't paid extra but as i said, sometimes it is included in the fees, you pay it, but then when you look at the receipt, the amount is different, but you can't complain, because if you do, and even if the officer dealing with you is an honest guy, someone in the back will halt your work unnecessarily.
If you only have to pay tax, get in line and pay them. Don't worry about the sticker, if the policeman has to stop you, he would stop you even if u have the sticker pasted on wind screen, he will ask for something else. Therefore, dont worry about the sticker, it is useless for the purpose you want it for.
Every car had all its major documents like sales receipt, registration receipts, duty clearance (on imported cars), etc. filed and kept in the excise and taxation department. Since a few years, the excise and taxation department has started handing over the files to the owners, thus, it is called return file. It is a very important part of your car i would say, just like original number plates, original registration book, etc.
When buying a used car, it holds equal importance as that of number plates, etc. If your file is not returned, i.e. is still at the excise and taxation department, the buyer of your car may ask you to get the file first and then proceed with the deal or he can may be cancel the deal as well.
My friend paid 7000 rupees to obtain his file from civic center. My father also came to know about this when he was buying me a small car, then he got his file as well.
To know whether you have the return file of not, kindly refer to the original book of your car (the passport type one) and search it for a red colored rectangular stamp saying 'the file of this car is returned', the stamp will most probably be somewhere or near the last page of the book.