Range from the cheapest window sill replacement £300 (Trading Interiors Ltd based in SM1) to the dearest window sill replacement £700 (MM Carpentry Building Services Ltd based in SM5).
Comparing carpenter and joiners estimates for replacing a window sill gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes to replace a window sill in North Cheam by posting a job with HaMuch and we will send it to carpenter and joiners in North Cheam.

"2 x Internal window sill replacement. Windows are UPVC and the sills are wooden and rotten. Approx length of the sills - L:107cm x W:27cm. Possibly need one wooden window frame replaced too. Just sill/frame installation as I am happy to seal and paint them myself. To start ASAP please. Many thanks"
KT4