Oil filter help please

This is very strange and confused Halfords and also the Citroen Main Dealer mechanics.

I purchased a standard Citroen C3 1.4 HDi 2006 Oil Filter from Halfords and subsequently a Citroen Main Dealer and neither of the oil filters would fit into the oil filter engine inlet connection on my Citroen C3 engine (see pictures).

Attached are 2 pictures showing the problem. The left picture shows the standard Citroen C3 Oil Filter Inlet Connection looks like and what the Oil Filter will go into. The right hand picture shows my Citroen C3 1.4 HDi 2006 Oil Filter Inlet Connection and annoyingly standard C3 Oil Filter won't fit into it

Halfords / Citroen Main Dealer don't know whats going on. Can anyone tell me what Oil Filter goes into the right hand Oil Filter Connection Inlet ?
This is a real mystery !!

Both the oil connection look the same, but the one on the right look as if there is part of a previous filter still fitted.

They should come out whole, but looks like this one has separated. What does the one you removed look like?

Use only quality oil filters like this one on Euro Car Parts for the C3 HDi engine.

The base on the one on the right is metallic and just won't budge. The base is fixed solid and feels part of the housing. It does not feel like the left overs of a previous oil filter.

I'm wondering if its some sort of oil filter adapter which someone has fitted.

Either way the standard Citroen C3 Oil Filter just won't fit in.

No one has seen anything like it.

This picture shows the new Citroen C3 1.4HDi Oil Filter on the left and the used Oil Filter I took out of the Oil Filter housing on the right hand side.

They are both almost identical in height, width and depth but the official C3 Oil Filter on the left hand side has a small plastic guide located at the top of the oil filter and the used Oil Filter I took out does not have this plastic guide. Very strange.

The oil filter aluminium body can be changed, it's got the oil cooler on it. Maybe it's not the original oil filter housing? Maybe from a similar model, something older that doesn't have the pressure relief hole?

As you say, I have never seen one without the hole that gets plugged by the o ring on a spigot.

Any part number on the old oil filter may show up a use for a different model?

Could it be a Purflux L343C oil filter which has sheared off at the base? May be worth a Google search.