http://www.paintballmarbella.com/index.html

http://www.absoluteaxarquia.com/attractions.html

Thanks, I've emailed Paintball Marbella. Hopefully they're open.

By any chance does anone know off-hand if Quad Biking, karting etc eill be readily available at the end of March?

check out the 2nd link that i posted, there are all kinds of activities including quad bikes, karting.

I did, but they don't really give any details about when they are open (i.e. do they close for winter). Im getting no response by email either

You need to click on the actual link itself ie. karting link. However for Karting there is a nearer one which is in Mijas Costa. I know it's open all year because my brother takes his kids there.

Take a look at this link

http://www.guidetothecosta.com/indooroutdoor.asp?destination=2

It looks like you may have to may have to call them.

Best of luck