DATA Device issues - no use siince purchased

I received a data device and when i finally managed to connect it to my phone it didnt allow any data usage. Since this i have contacted the helpline more than 6 times....replaced the device in their service centre....replaced the sim card in their service centre....had a technician visit and sort it out.And now again its doing the same thing. It connects with the device, but doesnt allow Data usage!!!<br> <br> I need this to be sorted once and for all. I want my money back for all these months that I had no use from it.