unit never works

I have been a Altech Netstar client for the past 5 years in this time I have had to replace the unit 4 times!!!!!<br> and again its not working and the call centre tells me I must take my car to a fitment centre to check it??<br> but when they installed it they came to me why not now???<br> <br> I also want a full refund for the last 3 months as I have been paying for a broken unit