If you bought off Ebay you will be able to get your money back if you open a not as described case with Paypal but you will have to send them back at your own cost (as long as that is how you paid).
The seller may reimburse you for your p+p but i ca'nt see them paying anything else.If the one's you bought are from the seller mentioned earlier in this post i would take a look at their negs

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If negs do'nt bother them at all then what else can you do ?.
If you paid to have them fitted do you now have to pay again to get them removed ?.
Best advice i can give if seller does'nt play ball is get what you can back through Paypal and move on.
You could go down the small claims route but like i said earlier,even if you win there's no way you can force the seller to pay you.It is a relatively small amount and could end up costing you more in the long run than you stand to get back.
Trading standards will quote law etc all day long but putting it into practice is a very different matter.
My guess is that you will contact seller and they will ask you to return them for a refund.You would have to send them back by trackable method (signed for) at a cost of about £15-£20.Seller may or may not refund your return costs although a good seller would.
You never know,seller may refund your total costs but i would'nt hold your breath,their negs speak volumes.If the link on page 1 of this post is the exact seller you bought from then they do not have a legal returns policy on the actual listing so you may well be entitled to a full refund and they would have to arrange collection at their cost.Putting that into force is another thing entirely though !.