I happened to use Clay Sim card for UK and let me tell you it was the worst that i have ever used in long long time. My sim card wasn’t working ever since i landed and despite several calls to the customer centre, they just said rebooting the phone is the only option that will work which clearly wasn’t working for me!! A bunch of idiots sitting behind teh phone and making it worse!! Apparently the sim never worked but these guys were pretty quick to send me the bill worth 1000rs for something i never used!!