Seems that problem has arisen before. Have a look here:-
https://community.bt.com/t5/Bills-Packages/Online-order-error-message-Ref-CON-0067/td-p/1587749
Here too:-
https://community.bt.com/t5/Bills-Packages/Ref-CON-0067-I-see-this-is-a-common-error/td-p/1647961