It depends on the Data Package that you subscribed.
default is, SMS "Bal" to 1355
Or dial *102# for data + minutes offer.
Edited by @Aj
Is your account is prepaid or postpaid?
if its postpaid: You can send rewards to 1233 and you will get all the details required.
You can download Du application. It is the best way for monitoring.
How to check my balance and data 0543XXXX97
You can either upload the App and use my account to view the balance or you can send reward to 1233 and you will get a notification with all the details of your account.
Thank you for contacting us.
If you are a post paid; send an sms writing "Rewards" to number "1233".
Otherwise download Du application.
I hope this number is under Du services because the code "054" is Etisalat.