Online purchase

the_lunatic_is_in_my_head

Hello OP

There are two circumstances where the right to cancel may be lost 

in the case of a contract for the supply of sealed goods which are not suitable for return due to health protection or hygiene reasons, if they become unsealed after delivery;

but you say it wasn't sealed so that doesn't matter and 

the supply of goods that are made to the consumer's specifications or are clearly personalised;

This would mean you ask for something specific such as a certain length (made to order or such is not relevant).  

If the second doesn't apply you can cancel and unless the trader told you that return costs are on you they have to cover that as well. 

If the goods don't match the description you can reject them outright for a full refund within 30 days (again return costs are on the seller). 

If you have an address you can chase them via small claims, starting with a letter before action, if they fail to honour your rights but speaking to your bank about a chargeback would be easiest to start with if the hairpiece doesn't match the description.