Livpure — Charging for spares during warranty period

I have purchased AMC regularly since i have been using this product for 6 years. This year i have issues with my RO and they say that membrane is not under AMC. However, i'm still not convinced that this issue will be resolved as the engineer is performing trial and error. A week before he said that the motor is at fault and changed it and it didnt work and now he says that membrane is at fault. What if it doesnt work ? When trying to sell AMC, they say it covers everything. Why so much lies to sell your product ? Why cant you be honest ?