Im giving you the simplest of all options, The way I see it, you take out a saturday or sunday to fix this issue. It can be done very easily in one day. The reason it has failed is because the user never took care of it, just like any other appliance, if you treat it bad, dont care for it, it will fail.
However if he want to apply "hawaai tukka or jugaarbaazi" its his choice and time, If he is comfortable in spending 5 or 6 weekends with the same problem then good for him. Im sure that 99% of PW users employ their mechanic to do their work, so why not get them to do it correctly. You just need to tell them to
change all tikki (both manifolds are removed for this)
change water body and metal pipe
change radiator + hose pipes
install new clips, thermostat and radiator cap.
fill with new coolant + water mix
How is this complicated? You just have to say with with ones mouth. He might need to help along if the mechanic is seriously lacking listening skills or is hard to hear or is slow to understand.
I see my time as valuable and usually do a repair job to its full extent to ensure the car doesnt break down on me when I least expect it. e.g. on the highway between a pack of wild wolves.. It wont be nice news to your family that their husband/son/father etc etc was eaten by wild wolves or wild boars.