Error page displayed to customers

Hi Our customers are unable to process the payment and receiving the following message, can you tell me how to fix it?

This is a notification that a request for payment failed for the online store.
An error page was displayed to the customer.

The following error was found:

x_fp_hash : Could not validate the integrity of the payment from the transaction key, x_fp_hash, x_fp_sequence, x_fp_timestamp, x_amount, and (optionally) x_currency_code and x_fee_amount values of the request.

https://www.ads-software.com/plugins/wp-payeezy-pay/