Builder Job - Ashley, KZN, 3610

We had a strelitzia growing outside our granny flat bedroom window which got bigger over time, and it was discovered recently that we have termites which have eaten away at the wood at the bottom of the window. The granny flat is one of those Witch rooms which were popular in South Africa in the 70's and 80's. The strelitzia was cut back and yesterday the roots were dug out, exposing the window. I'm not sure exactly how this can be repaired, but I would be keen to hear if anyone has any practical, creative, and hopefully, inexpensive ideas. I originally advertised for a carpenter, but didn't have a response.