Invite your friends to try Cert. and for each friend that signs up, we will give you £5 to spend on your next refill purchase.

Your friend will also get £5 off their Cert. Starter Kit - everyone's a winner.

*Terms & conditions apply.

How it works


Share your unique link with friends, family and people you're fond of.

Your friend makes a purchase

Your friend clicks your link, signs up with their email and gets their £5 voucher code to spend on their Cert. Starter Kit.

Get £5 off!

When your friend makes a purchase, you’ll get an email with your £5 voucher to spend on refill packs!

*Terms & conditions.

Refer a friend only applies to new customers. Customer must sign-up for an account via the referral link to claim their £5 voucher. Only one voucher can be used per order. Voucher cannot be used in conjunction with any other offer or discount code. Voucher can only be redeemed against Cert. starter kits and Cert. refill packs. Cannot be used for replacement parts or accessories at this time. We reserve the right to end this promotion at any time.