I got a dongle on 3 in the summer of 2009. Later the same year and again in early 2010 I told them it was not fit for purpose as it did not recieve a useable signal in spite of their assuring me that it should.
3 were unable to remedy this but I continued to make monthly payments until the contract expired (the dongle was thrown in the bin long ago). When the contract naturally expired at the end of May 2011, I was annoyed to see they had taken a further payment from my bank account in June 2011 to which they were not entitled. I cancelled the direct debit.
Now they are harrasing