will bypassing a Heater core, cause other issues, please read below, Thank you

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my heater core began leaking around summer time this year, it was dripping in the floorboard even though it was still working, we decided to take it to a mechanic and they bypassed the heater core with hose connector disconnecting the heater core, two months after we decided to get the heater core replaced by a certified shop. They forgot to put the installation back, so we could hear the engine from the inside and we seen water under the truck. We took the truck back the next day, now the water pump is leaking. they said it was because of the bypass, they had the truck another week, got it back the next day it was pouring water again, this time from the thermostat. I pick it back up today and the wipers constantly stayed on and would not go off and there are wires showing around the column on the boot where the shifter goes but claim they did not touch the switch even though our tuner button is broken and my headlight switch went out

How long has your 2004 Chevrolet Silverado 2500 HD had this problem?

Few months