If you receive faulty goods and wish to return them, The Distance Selling Regulations are in addition to your other legal rights.
So, if your goods are faulty and don’t do what they're supposed to, or don’t match the description given, you have the same consumer rights under the Sale of Goods Act as you have when buying face to face.
Any terms and conditions that say you must cover the cost of returning an item wouldn’t apply where the goods being returned are faulty.