2002 Mitsubishi Triton head gasket

Engine Mechanical problem
2002 Mitsubishi Triton Four Wheel Drive Manual 196000 miles

Hi there,

My car has had high oil pressure and my mechanic started by looking at oil pump, after finding no fault(9hrs) he tells me oil filter housing has valves, so he looks there and finds damage which is now fixed(4hrs). Puts it back together then says head gasket is gone so we fix that. Upon tightening head he strips thread and has to throw away gasket and helicoil new thread. My question is should I have to pay for the first 9hrs when there was a cheaper fix to look at first and should I pay for 2nd gasket plus labour to re do head? Surely stripping a thread and the wasted gasket is on him as its poor workmanship