Altec Netstar damage the airbag on my car and they refuse to pay back the money i paid on fixing airbag

I have send my car to one of Alteck Netstar tracker installation centre around Pretoria Cnr Pretoriuos and nelson mandela street, the service was too bad , when I come to pick up my car after they finish to install a new tracking device I realised that the airbag light is on, I told one of the lady who is a sales manager but the attitude was to bad ,she said she can only fixed my car next week ,I ask her if the people who are going to fixed my car are accredited she said no they are not , I told her that my car is still under motor plan I cannot take my car there because if something happen the warranty cannot cover my car, so we agree that I must take my car to dzunde auto solution because the are accredited I took my car there they try to fixed the problem but not successful they then refer me to airbag specialist (National airbag services ) and they fixed the problem and reset airbag system. I then take the invoice to Netstar installation centre and they refuse to talk to me they said is my problem and they are not going to pay anything I then lodge a complain to Netstar head office until today my problem is still not solved , I requested them to remove there are tracking system since the are failing to resolve my problem no one contacted me since last year December when I call they said we are going to call you back , on the 15 January they debited double amount premium on my account when I call they said it was mistake but they don't want to accept they mistake of tempering with the airbag on my car and they are also giving me bad attitude .