How can I buy GP 1gb for 7 days?

GP 1GB Internet Pack :

• 1GB for 7 Days (Activation+6) days at Taka 89.
• Recharge 89 taka.
• This campaign will run until further notice.
• Dial *121*1*4# to know internet balance. 

You can check here also GP 1GB Offer 2020