You’ve said that you don’t have a paint code sticker. VW used to provide two data stickers for their cars - one located on the boot floor or in the spare wheel well and the other in the service book. If you don’t have either of these, then there’s a 2004 thread that lists paint colours, this list was taken from a Golf forum so may not list the colour and paint code of your Polo if the colour of your car wasn’t a VW Golf colour.
viewtopic.php?t=4712
Failing that, your local VW dealer should be able to tell you or find out your paint code, or a good bodyshop should also be able to help.
Alternatively, if you’re able to post a picture of your car, there maybe another forum member who owns (or has owned) a Polo that’s the same colour as yours who’ll know what colour it is.