Best hardwood for window piece?

Hi, I have an old PVC window which has a piece of wood between the base and the concrete window ledge. A few years back it rotted and I had it replaced but it's rotting again, I think it was softwood. Can you recommend a good hardwood? It's going to be painted. Window sills seem to be made of meranti, would that do the trick? Size is approx 49 x 2.5 x 2.5 inches (or 1250 x 60 x 60mm). WouldTravis Perkins or a local timber merchant cut it for me? Thanks

a yard near me sells door sills and window sills quite cheap, he has lots of seconds and overstocks on clearance. As this is a coastal area with boatbuilders he also has oddments of teak and other stuff. I don't know if there are lots of other yards like that. Sometimes you get oddments on ebay. you would have to cut it yourself, and if it was me, I would soak it in a tray of wood preserver for a couple of days, especially the ends, and let it dry out well before fitting, as you have a history of rot. Are you sure it is draining properly? A spacer underneath might prevent trapped water.

pvc trim might survive longer, or clad the timber to prevent it rotting.Whats the purpose of the timber?

Thanks for the replies. I have three windows in the front and they all sit on a piece of wood. Maybe the previous owner got the wrong sized windows as I can't see a reason for it! This is the only one that has rotted so yes, water might be getting trapped. My local Travis Perkins has stock of red grandis so I'll have a look at it.