Your post is somewhat confusing. It sounds to me that something was sent from China and became damaged in the post so the Royal Mail put tape on it.
Read the link posted by @john1297576
You must open a "not as described case" from the item. Do not try to get a replacement. Get a full refund. Use the eBay system and do not do any other action suggested by the seller.
You will be required to send back whatever you did receive and the seller should send a label at his cost.
When you open the case he has 3 days to supply the label. He may say that he cannot do that but if so simply escalate the case to eBay after 4 days. Do not contact the seller simply follow the eBay case.
@lazaros.m