Charging 1Lakh + rs for motherboard fix.

One day my laptop showed black screen and it was not turning on turned out it's one ram and slot is not working. Currently I'm using my laptop with single 8gb stick.I contacted the lenovo service and they are charging more than 1Lakh rs to change motherboard ( laptop costed 76k).I denied by saying it has started working fine. My laptop is out of warranty but I'm thinking to extend it's warranty by 1year which will cost 7.5k and then wait for 1 month then insert the faulty ram and raise complaint that laptop has stopped working so they don't charge me such a hefty amount. Will this work? Or will they still charge for repair coz issue happened during out of warranty period?