While I agree about Nissan, BM, what you have to remember is they would know it was going on a Zed. So they would know what the application was going to be. Did the seller know what car these were going on? If they did, then that is bad of them, but they seem to beleive that they are the right sizes. The seller, although not the best, has advertised exactly what they were selling. Thats the problem with eBay, while although cheaper than other places, you dont get the confidence of the sale and you have to know exactly what you are after.
I would though, approach them and try and guilt trip them into it. As you say, mention that it could be dangerous and may cause an accident as it is outside of spec. Might be able to get them to meet in the middle.