The Century maintenance batteries sold, delivered and installed by this service have nationwide warranty. Once the battery assist staff arrives, he will perform a complimentary check on the car charging system to make sure that the alternator is working. Plugging in a new battery will still not solve anything if the car has a faulty charging system. If that is so, they also provide a service by recommending towing or workshop services if and when required.
The Century maintenance free batteries provided in this service scheme is the Century Marathon battery, which is Century Batteries' mid-tier battery out of a line-up of three. But one should also note that this service is a cash on delivery (COD) service this means you should have cash in hand ( in Malaysian Ringgit) or you should make your way to the nearest ATM or you could try begging someone for cash if its in the middle of the night.
But do note that the company provides only batteries that regular cars use. Those that use certain European make cars especially from Audi, Volkswagen, Mercedes Benz may not be able to utilise such a service as these cars usually require batteries that aren't in the usual NS40, NS60/70, DIN55/66/88 batteries. These are batteries usually made by Varta and have serial numbers which you have to key into the car's ECU to get it to work. So tough luck if your car battery conks out in the middle of the night (usually it doesn't as these batteries are huge and usually last about 3 years from experience).
So anyway, if you do get stuck in the Klang Valley with a normal (usually the common Japanese, Malaysian or Korean car) you may not worry too much as there is a service that will deliver a battery to you.