If you kept your booking you would be put on the new fight free of charge.
If you opted to cancel a ticket and take a refund or a voucher then their obligation to provide care for that booking ends and your money is either returned or you hold the value of the ticket as a voucher you then exchange for whatever one of their services you wish...up to the value of the voucher. If you opted for a new flight and they reinstate the original one then you could ask to be moved back and they may do as a gesture of goodwill, but they are under no obligation to as you accepted the new flights when offered.
Trading standards won't have anything to say as nothing wrong would have happened.