Cycling in Melbourne Australia
The battery packs and chargers are pretty standard, no need to chase a Phillips dealer in particular. I think Phillips themselves will be quite expensive, especially the fact they are well known brand.
If your bike is 200 Watts then a 36V charger will do the trick, don't get a charger which outputs more than 2 Amps, it will reduce the lifespan of the battery. If you have a bike with more than 200 Watts output, e.g. 500 Watts plus then the chances are good that the battery pack is 48V and you need a 48V charger. One can easily check the voltage with a multi meter if you are unsure.
I assume the battery pack is lithium or is it lead acid? Let me know how you go and if you need help from this end, always keen to help fellow ebike riders where I can :-)