Likes Bikes and Dirt
No. Warranties are an obligation of the retailer to repair or replace the products they sell if they are proven to be faulty. Warranties are a legally binding agreement but even then do not substitute or override consumer law which offers greater protection again, as the product must be fit for purpose which often extends well outside of the manufacturers timeframe.Warranties mean diddly squat in Australia - bike or cars or anything.
As an example if you buy a bike with a 12 month warranty and the frame snaps after 13 months the bike is/was not "fit for purpose" as a frame should last longer than barely a year and under consumer law you would be entitled to a replacement. This is an example only.
On a tangent, the thing with bike warranties that shits me the most is when they replace the "frame" but refuse to fit the parts from the old bike or worse yet, if the specs change they make you buy replacement parts to suit the new frame. This is a breach of consumer law, but I digest.
Ultimately the issue lies with how far the consumer wishes to push the issue as if the retailer and/or manufacturer refuses to honour the warranty or consumer law then your recourse is ACCC, which are a toothless tiger, or court proceedings.
You will need everything in writing however so yes, an email to the store detailing all the issues is vital to get their response.
OH64 best course of action now/after the response, is to call the manufacturer (or their agent) and attempt to deal directly with them. If they still get no joy them Merida directly and then ACCC or then court.
Proving the brakes were contaminated by the store should not be difficult, unless the store can demonstrate that the OP or a third party has attempted to service/fix the braking issue and contaminated the pads themselves. If not then the fault will lie either from the part of the servicing agent.
Good luck with it and like many things in life you just need to be patient and persistent and never take no for an answer. Giving a rightful mouthful to a rude and useless mechanic/owner does not forfeit the law so make sure you continue to stick it right to them.