Maruti Suzuki India — Car key fob batteries

I have a Maruti Baleno which I have been using for two and half years. After one year the batteries stopped working and I was told the batteries need replacing. I was a bit surprised. Anyway I changed the batteries. After another year the same thing happened, This time I asked the workshop manager why this is happening every year. Usually key fob batteries last for 3-4 years. I was told Maruti car batteries last for one year. I am writing to ask you if this is true and what is special about the Maruti cars that the batteries last for one year. Anyway after the job was done I received an email from the workshop that said the parts and labour cost for the job is Re. 0.00. But to my utter surprise I received a bill when the car was delivered.