18 year old system from netstar

I signed up new contract for 36months top plan with netstar 6months ago , replaced 2 battery's , took the car to bmw , the cars alternator is 100% working order, the battery has been going flat none stop and today to find out the netstar technician linked the new system to the existing 18year old system dated 2001, the car was standing 2 days and i had to buy a car battery charger , to charge my 3 month old battery , (second one) the technician at the call center that the system(netstar) has its own battery, when we wanted to start the car 2 days ago, car was dead, took the battery out to be charged Netstar didn't notify us tampering of car battery to proof there system dosnt work, secondly , they told us the new system is pagibag ride on the 18year old system that was never removed from the car, what will happen if i am now in a emergency and the netstar has drained the car battery dead....... it puts me at risk my car at risk, i have lost R1800 for new battery that wasn't necessary firstly , secondly paid R600 for a car battery charger to charge a 3 month old (new) battery,I A M F U C K E D O F F of this bull****