Bad bad service!!

I ordered 2 Internet wifi devices, one for me and one for my sister. The device for my sister didn't fall in range of their services. I returned the device, neotel then cancelled my device, leaving me without any access, then billed me for the non receipt of this device, I received no credit for the device returned to them and according to their records I still have thAt device, in the mean time they have handed me over for debt collection as I haven't paid for the device?? I am at no position to sort this out since last year October, as I phone get a reference number and nothing happens!