Seller's error: who bears the costs?

Several months ago, I bought a new television from a major retailer and paid for the carefully selected model, which an employee loaded into my car. Now the salesman has contacted me to tell me that I have been delivered a visually similar but technically different set. He asked me to return the device or pay the difference in price! I find this kind of behaviour unacceptable. What do you think?
Claude
Under Swiss law, good faith is presumed; it is a cardinal principle of our legal system, enshrined in article 3 of the Civil Code. You state that you did not notice the error, which is plausible if the TV you received is similar to the model you ordered. In the absence of evidence that you deliberately took advantage of the situation, you cannot be accused of any contractual fault.
Conversely, an error made when the product is delivered is the responsibility of the seller, who must accept the consequences of his actions, unless he can show that the buyer played an active role in the misunderstanding.
However, if you receive an appliance worth more than you paid for it, you could be considered to have benefited at the seller's expense. Under Article 62 of the Swiss Code of Obligations (CO), anyone who becomes rich without just cause is obliged to make restitution. However, this obligation must remain proportionate and reasonable.
In practice, this means that if you do not wish to keep the faulty and more expensive product, you must allow the seller to recover it. However, you are under no obligation to do this.
Admittedly, according to Article 74 of the Swiss Code of Obligations, where the obligation relates to a specific thing, the place of exchange is the place where the thing was located at the time the contract was concluded. In this case, the place is the shop where the TV was loaded into your car, which means that the seller could try to demand that you return it to his premises. However, such a request would have to appear reasonable: if, for example, the shop is far away, the item is bulky or returning it would entail considerable expense or effort, the seller would have to organise collection from the home of the purchaser, who is not at fault and acting in good faith, and who would not have to bear the costs. It goes without saying that the seller will also be obliged to supply the product originally purchased.
You are therefore under no obligation to return the item yourself, or to pay the difference in price, unless you voluntarily decide to keep the more expensive model. On the other hand, you must cooperate to enable the seller to exchange the product at his own expense.