Simply head to
www.cinchrewards.co.uk/mumclub, enter your details into the claim form and wait for your claim to be validated. You will need the unique reference number provided to you in The Mum Club newsletter, and the order number from your cinch purchase which can be found in your order confirmation email. Once your claim is validated then the £100 cash back will normally be paid within 28 days. Please see the full T&Cs
here and Promotion Privacy Notice
here.