Hi IrKirsty,
It sounds to me like you have been sold human/synthetic mix hair. Was the hair branded?
Unfortunately there are alot of companies that buy in bulk from abroad and will end up with this mix hair, but label it as remy. Sometimes the company selling it doesnt even know, as they ask for remy when buying it from their suppliers and then just trust they have been sent the correct product. They should have checked it, and you are entitled to refund, as the product is not as advertised and not fit for sale. I can then be deemed as faulty. (i run an extensions retail site myself, so know customer rights).
If you are looking for extensions in future then research the top brands. Beautyworks is a great brand, the price matches the quality... beautiful hair. Or for a cheaper option, but still Remy hair, try Halo... Both of these brands i have sold, and worn myself, and installed on clients and they are lovely quality, last a good length of time and can be straightened.
As for getting your money back, id try contacting the company again to return for a refund under your consumer rights. If they give you the brush off again then ask your local citizens advice bureau if there is some action you can take to get your money back.