Why... we're not paying for him, Ecuador are.
Let them get bored of it, maybe they'll learn not to jump on political bandwagons next time (I bet it's hurt their political negotiating power with the UK since day one).
When they're bored of it, we have to start paying the same amount anyway to imprison him. Let them fund their own stupidity, and take out the difference (e.g. policing) from their next trade agreement with us.
They were hoping to use him as leverage but that obviously doesn't work out unless we actually want to deal with him.