OH bought a hansgrohe shower in January 22. The main shower head is not working properly. He bought it from Castorama.
The shower manual says the guarantee for the shower is 5 years. The Castorama receipt says the guarantee is for 2 years.
Which takes precedence?
Two years from January 2022 can’t take preference as it has expired.
The manufacturer’s guarantee will have to be referred to them.
I realise that! What I want to know is whether the five year guarantee has any validity and is meantingless once the shop 2 years has expired.
I suspect Shop would have refunded or given replacement within the 2 years. Now they’ll wash their hands of it?
You have the proof of date of purchase and can use that to show the Maker that the item is still within the 5 years of Their guarantee…
You might get lucky and find the shop will send it back on your behalf 
I would expect you to have to contact the maker. They may well have a warranty return and collection system for things like this, and it may be reasonably simple.
Is it furred up?
No evidence of furring but I gave it a good soaking in détartreur and it is now working, fortunately.
I have been interested in your responses anyway in case we find ourselves in this situation with something else where the manufacturer guarantee is longer than the shop’s.
No, it’s definitely not meaningless. This is known as a “commercial warranty”. It’s in addition to your statutory rights, i.e. the 2 years you’re entitled to by law from the retailer (who your contract was taken out with).
They’re two separate things, and in the same way that you’re statutory rights can’t be overridden in terms of the retailer’s obligations, the commercial warranty isn’t affected by the retailer’s statutory warranty expiring.
Thanks Gareth, that’s exactly what I wanted to be made clear to me. 
Just to expand a little on what @Gareth said, a commercial warranty can have restrictions placed on it that it would not be possible to place on the statutory warranty. These restrictions should be in the warranty documentation that came with the item, but they don’t necessarily have to be.
And does anyone ever read it?