Hi, I'm Trying to subscribe using the 70% discount offer but Unfortunately Couldn't, please try to solve this problem as soon as you can and get back to me,

Hi there, setika-sabrangi.

I've checked here and found out that the current discount rate is 50% off for 3 months. Please browse this link for more details: QuickBooks Online Pricing.

Can you share the page where you see the 70% discount? 

I'm adding this article regarding a subscription charge from Intuit or QuickBooks Online: How to understand your subscription rates and charges.

I'll keep this post while waiting for your response. Take care always!