I had used an Australian Sim card from Clay and returned when i got back after 21 days. When i got my bill, I had to recheck my call records twice cz my bill of rs 28k for 21 days. Turned out that i was billed for calls made by person who used the number before me and for most of the calls, there was increase in the duration by them. It took me a week to get this sorted and to finally pay my bill of 8k!! Never using this again