Sorry, I am bit confused. Why service center needs a Fastag sticker which you claim to have installed by manufacturer? (As far as I know, Fastag is the system and RFID is the technology so both are same in terms of usage). Please clarify with the service centre that the sticker installed by the manufacture is really a Fastag sticker or something else? ?
Also, are you regularly recharging that fastag/RFID fixed on your car windscreen?
(When I bought my Tigor last year, the dealer advised me that Fastag is compulsory for Registration and as such he charged me Rs.600 for same. He bought a Fastag from Paytm without my KYC details and handed over to me on delivery of the vehicle. When, I tried to upload KYC details, there was some error coming from Paytm system, hence I did not follow up further. Now, since Fastag become mandatory, I purchased one from ICICI and pasted on the Windscreen. So, it is the dealer who arranges Fastag initially for registration purpose which can be also used further if needed, provided we recharge regularly ).