The central locking has failed in the harlequin. It looks like it's the pump as it has corrosion on the circuit board.

 

My question is are all the pumps compatible? 

 

There's a few variants that all look the same and have the same part number the only difference is they have no letter or 'A', 'D' or 'J' at the end.

 

Mine has 'D' at the end but would say an 'A' fit?

They should, I believe they are only revisions. Just be sure to get the same 3 door or 5 door to yours. You could also strip yours down clean the circuit board and see if the actual unit works, if not one from the scrappy shouldn't be more than £30.

 

These are well known for going as water gets in so it's worth putting the new one in a bag.