Simsim — Charge dispute form

I ordered pack of 10 designer face pollution mask. I got the delivery today but the pack has only 9 masks. I had booked COD order so I paid total amount including shipping and I did not get total 10 masks. I requested them to send me the one missing mask they said no we cannot, than I said exchange it send pack of 10 and they can pick up this pack of 9 again they said they do not have exchange policy, I said i would return this product but they said it is a non returnable product. I said give me cash refund as i paid cash they said not possible we will send the refund link in 5-7 working days. I said I will not click on any random link, who knows by clicking on the link they may just hack my mobile or laptop.. I do not trust this people as i have been cheated and they do not have any policies or procedures in place. I have not seen such a bad customer service ever.