I had 2 international sim cards for eastern europe (10 gbp plan)from matrix cellular on 22 april 2012. They took a security deposit of rs. 12000 for the same before giving the sim.
On my return on 6 may 2012 I was issued 2 bills 1 was rental and 1 was itemized billing. In the itemized billing the phone nos. Of the calls with most talktime were missing. On calling the customer service I was shocked to hear that matrix had no record of these nos. And she told me I had no option but to pay for them as the bills were ’genuine’. They kept on insisting "sir, our bill is genuine and you have to pay " without giving any further details .
On the whole their attitude seemed like ’we have got your money and you have to accept our terms if you want any of it back’. I am surprised that these guys do not understand the importance of proper billing especially in the calling card domain.