Yes, as customers who are not up-to-date with their monthly payments no longer qualify for SDC UK's Lifetime Smile Guarantee. For more details, please refer to the relevant FAQ explaining Lifetime Smile Guarantee of SDC UK.
Yes, as the Lenders may provide information about missing payment to credit reference agencies (CRA) and this could make it more difficult to obtain credit in the future. It is therefore very important that you keep up payments on your loan. If you are requesting a refund from SDC UK, it will be processed as a usual claim alongside other customers and creditors of SDC UK.