If you have problems with ordering the VPS hosting due to technical reasons such as page reset, error message, etc., you need to make sure you have enough funds to pay for the VPS services.
Most likely, the amount of your free margin (without bonuses) is less than required to pay for the VPS hosting. Therefore, the system cannot fulfil your order.
In case you have enough funds in your account, you should contact the support service, specifying the account number and the IP address of your server.