I would like your advice on whether to accept repair and rebuild transmission instead of replacement of transmission on my 523i 2009 BMW.

I have a BMW 523i 2009 vehicle. The car reached almost 200,000km, near
the end of the 8 year 200,000 km warranty. A transmission problem was
detected. BMW only replace transmission. The country agent is proposing
that they check and repair and give 6 month warranty, as the cost is very high
US$ 15000. Should I insist that they replace or accept the repair option as the
problem could be simple.