Could you please recheck about hire cylinder again? because our staff has confirmed that in June'2013 around 03/06/2013 - 07/06/2013 we had returned empty cylinder to your driver (see detail as below).
But the invoice no.90155010 that you charged of period 02.06.2013 to 01.07.2013 you did not deduct empty cylinder that we returned, until the last invoice no.90156008 still charged us as the same.
Hence, kindly check your documentation for the return cylinder at the time again ASAP. We would like to clear the issue before order to pay the last invoice.