Warranty coverage 10 days beyond 5 years - questionnable

Bit of bad luck with 2012 Cruze LT. 113,000km on 160,000km Powertrain warranty, but 10 days over the 5 year limit. Car went in for factory water pump replacement after over 1 year of chronic antifreeze loss, and repeated dealer visits, which has also led to full warranty repacement of:

• tstat housing,
• intake manifold (due oil leakage into charge air, etc. from failed rubber valve). Had also reported heavy brown sludge build up on underside of oil filler cap at that time.

Early March 2017, the car started having reduced power, and top end ''ticking'' engine noise ,just before the appointment, and about 10 days after the 5 year powertrain warranty expired.
I had noted and mentioned various oil leaks, and heavy brown sludge, maybe 6mm (1/4in thick) on underside of oil filler cap. Oil looked ok.
Dealer found

1. Leaking axle seal
2. Oil pan gasket leaking
3. Oil cooler/filter housing assembly leaking ('' not serviceable = replacement !)
4. Oil cooler to radiator hose leaking (ok - not really power train)
5. Camshaft chain tensioner/guide block bolts had come undone causing oil to bypass block and chain, and apparently causing the ''ticking''engine noise. (resolved)
6. Turbocharger housing cracked (exhaust side - and same as many available web posting) Is this a chronic problem?
7. Dealer ultimately offered "standard GM post warranty'' 25%GM, 75% me, for all above, which I felt I had to accept to get vehicle back on the road.
8. Dealer replaced intake manifold assembly once again, but covered this on the previous replacement being deffective.

Car was always well maintained, Dexos oil & filter changes at 10% remaining life, not hard driven, mostly highway travel.
Though dealer service was good and provided free courtesy vehicle, we were quite disappointed with GM coverage provided, especially given 2/3 of warranty miles, and being just passed end of warranty. GM rep said nothing further could be done and case would be closed with ''not satisfied'' tag.

Has anyone successfully challenged on similar situation? Though we like the overall comfort and performance of the cruze, this is seriously making it difficult to consider future GM purchase
Thank you for taking the time to read this ! Regards