I recently secured an award for an oil recycling contract, which is to be executed by my subcontractor. However, after the award notice was issued, I realized there was a misunderstanding in the pricing due to an error on my part in explaining the scope of work to the subcontractor. Now, the subcontractor is requesting nearly 5x the original amount. How should I proceed to address this situation effectively?

Unfortunately I had my vpn turned on , And i got blocked, I have send an email to support team, No response yet! Requesting expert suggestions.