Unreasonable. This is equivalent to him selling the beads and rope separately. If you bought it in another house, there is a charge for exchanging it at his house. In our place, when the line is broken and the line is changed, the post-service is free, not to mention the first time. And you don't belong to changing lines, you are buying a commodity. If the wiring is not properly changed and the customer is not satisfied, it can only be said to be a semi-finished product.