Hell0 @Kiran8420,
I understand having a higher than usual invoice is never a pleasant surprise.
It's important to note that text message alerts are only sent for airtime minutes on plans with a set amount of minutes and data, it does not apply to any other service.
However, you do have the option to stay on top of your 1000 international minutes usage through the usage details on the Fido app to make sure that you don't go over and avoid overages.
Since you did make the calls then the charges would be valid, if you can not pay it all at once you can reach out to the Credit Operations team and set up a payment schedule you can get more info for that here.
