Such things are done to maintain and manage data load on the network. Mobilink joined the sms package race in the last because they were always concerned about the quality since majority of their revenue came from postpaid connections.
I have personally experienced text messages sent and/or received on ufone network after days of sending them.
Aur Bhaiyo, it doesn't hurt to spend a 100rs to wish eid to your loved ones 
Stick to warid. Its better than others
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