As per 'consumer contract regulations' (2014 version of the 'distance selling regulations' you have the right to a refund within 14 days.
Which Summary
But reading Cocosa's Ts & Cs, they say the following:
Returns Policy
Change Of Mind
A Return Authorisation Number (RAN) is required for all returns
You may be entitled to a credit, provided you return the item to us within 14 days of your order being dispatched.
The item must be returned to us in brand new condition, with the packaging and item being exactly as it was when you received it. All Products must be packed in the original, unmarked packaging including any accessories, manuals, documentation and registration that shipped with the Product
If the returned item is in a noticeably used condition, then a credit may not be offered. Clothing and footwear items may not be returned if they have been worn, or if sewing tags have been removed
Return postage will be at your expense
If eligible, we will issue you a Credit Voucher to the value of the item, once the item is returned and assessed
I don't know whether legally they're allowed to side-step the law with their own Tcs & Cs, you need to get in touch with a consumer rights agency.
When you've spoken to them, write to the CEO.
If technically they are allowed to do this, as they don't follow standard UK law on distance selling returns, they should have flagged that much more clearly on the website. I have never encountered an online shop that did not refund for a return within a stated time period, and I do masses of online shopping.