D
dextrous
You don't need a plumber to replace a durgo - if you can cut some plaster out to gain access to it, then it's either a pushfit one which will slip off easily enough, or a solvent welded one (ie glued on) which will need cutting off unless they didn't bother with the glue
You can then either replace it as it is, or extend to the loft space and put one up there, or take it through the roof and not need a durgo at all.
The second opition is a happy medium which will allow easy access for future maintenance whilst keeping any further smells that might occur away from the main living areas, although having chopped the plaster out in the first place, an access panel could be used to cover the hole rather than the hassle of replastering the area.
You can then either replace it as it is, or extend to the loft space and put one up there, or take it through the roof and not need a durgo at all.
The second opition is a happy medium which will allow easy access for future maintenance whilst keeping any further smells that might occur away from the main living areas, although having chopped the plaster out in the first place, an access panel could be used to cover the hole rather than the hassle of replastering the area.