Tankess Water Heater gone wacky!

Our tankless water heater has afew issues and I want to order the right parts to fix it. It seems the water temp can’t be adjusted and it’s burning hot, it sporadically supplies hot water during my shower - on and off and lastly, after the shower when the water is turned off, it overspills onto the floor! My handy man can replace the part if anyone knows the solution here. THANK YOU.

flow switch inside the unit is dirty or bad. i would suggest to have a professional tech come out and diagnose the problem.

thanks for that Mark 28

There is a thermostatic adjustment. See H on attached.
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