Best Anti Ageing Moisturiser I Had A Card Through The Post To Fill In And Return To Receive Free Samples Of Silkies Anti-Ageing Moisturiser

I had a card through the post to fill in and return to receive free samples of Silkies Anti-Ageing Moisturiser - best anti ageing moisturiser

I have the samples, but today received a new package that contains a moisturizer and eye and keep invoice for $ 13.98. I guess I have not read the fine print somwhere, do I pay?
Can goods?