My ****le doesn't work anymore

I bought a cell c data bundle for 12 months. prior to that my ****le was working fine. After using the SIM card on my ****le, I noticed that internet connectivity was not great but still working. I went back to cell c and the told me that there was something wrong with my ****le and that they could try and help me out with it. They tried to do a software upgrade instore. Immediately afterwards every time they inserted it in the computer, I stated that 'the device could not be detected'. I was advised by them to have them send the ****le to head office in Midrand for repairs. Now the repairs department wanted R228 to do a software upgrade. I cannot even do a software upgrade on the internet coz the ****le states 'device not detected'. However, when I went to cell c with my query, my device could be detected. This is not my fault