No and yes. If you pay by standing order then you have agreed to only pay x amount on y day. If you pay by DD the company taking the money can vary the amount they are taking without your specific agreement. They have to NOTIFY you but unless you specifically opt out or cancel your DD your money...
Outrageous if true. I once did business (not for long) with a financial services sales company (now long deceased) whose main sales tactic was to default 'add ons' (which they got paid for) to 'on' whenever they sold, without telling the client. This is the same thing. It makes me grateful both...