You cannot simply return something because it is incompatible with your existing products, it is upto the consumer to know this before making a purchase , if on the other hand the retailer had advised the consumer then they would be within their rights as the product would have been mis-sold.
An example of non conformity could be a box specifies the DVD player has an HDMI port yet on opening the box there is none, the goods now do not conform so the consumer is within rights to return the item for a full refund.
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Fitness for purpose, s14(3)
If the buyer expressly or impliedly makes his purpose for the goods known to the seller, the seller is obliged to make sure the goods provided are fit for that purpose, if it is reasonable for the buyer to rely on the seller's expertise. An example of the application of this provision can be found in Godley v Perry
Godley v. Perry [1960] 1 All ER 36 QB, p. 324
§ P bought a catapult from D and was injured when using it. D third partied the wholesaler and the wholesaler 4th partied an agent of its supplier and the importer. D said that when goods arrived in shop she tested the elastic. 3rd party called in the usual way at D’s business to sell the goods (both parties tested the toy). Previously, 4th party had called in usual way at 3rd party’s business (3rd party tested the elastic).
§ Court held that, b/w D and 3rd and 4th party, this was clearly a sale by sample and that the implied condition accordingly existed. Court found that goods, in breach of a condition, were so defective as to be unmerchantable. Counsel for 4th party submitted that the defect would have been noticed on a reasonable examination of the sample and that no condition should be applied.
Þ All that is required is reasonable examination, not every possible form of examination. In this case, pulling back the elastic was reasonable. Where there was no examination that was common in the trade, common sense standard of what would be expected in every day life is OK.
Þ 3rd and 4th parties were in breach of s. 15(2)(c) of the Act.
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You are right mate

it seems that because he has not asked the vendor about whether the goods are suitable or not it is unlikely he will get the money back. Only small chance he has is;
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If the buyer expressly or impliedly makes his purpose for the goods known to the seller, the seller is obliged to make sure the goods provided are fit for that purpose
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The wording, at least to me, seems to suggest that the vendor has an obligation to make sure that the goods are going to work when the consumer purchases them. i.e. they are required to provide their expertise, I can think of an example that whenever I purchase a PC game over the counter they always ask me if my PC is suitable for the product.
Unfortunately there is no case law on this area.
OP you can blaze a new legal trail and argue this in court! You will have a legal case named after yourself

but for all the hassle of that you may be better off just accepting your fate and taking the £200 loss.