Complain about my car Battery

in 2016 Sept i bought a brand new Sandero from Renault Durban, i have serviced my car at 15 000 km, yesterday 11/12/2017 as i was leaving work i got into my car and my battery was flat, i called road assist and they came to jump start the car for me, this morning 12/12/2017 i went to Renault Durban to ask them to change my battery and they told me ill need to leave my car as the process to change a battery takes anything from 3-5 days as they will need to get an authorisation from the maintenance plan, the funny part this is their maintenance plan and the service guy told me authorisation for one other client took a whole week, i do understand they have processes to follow but i cant be without a car for 5 days, so i asked the service manager if i could get a courtesy car and he told me they don't have any car. i have a 3 year old son which i drop and fetch at creche, if i'm out of a vehicle for one full week how do they expect me to move around, the reason i bought the car was because i have a need for it, i can understand them taking my car for a day not 3-5( its just a battery change something that will take me an hour to sort out at Battery centre). if they promised me a courtesy car that could work also but now i need to sort myself out for something that is not even my fault, this car is only a year old for the battery to be giving me such issues and its the festive now and ill be closing for the holidays soon and travel to Newcastle but if they take my car for so long how do they expect me to function, this is utter bull****.