Thanks for the clarification.
Users who have made payments with wrong amount are not recognised and you need to process such payments manually
So say the user pays 1 bitcoin when they were supposed to pay 1.00023 bitcoin. What happens to the 1 bitcoin that they paid? Is it at least identified as belonging to the merchant? The merchant still receives those funds after manual processing, yes?
It is impossible for each payment box to show a new unique generated bitcoin payment address for each website visitor
Why would you generate a BTC address for each impression? Typically an address should only be generated/assigned once a user is ready to actually make payment with bitcoin, ie final stage of checkout. I can't think there is all that much traffic at this point.