Learn English – it called when someone attacks a person and the offender gets an even worse reputation

I don't know of any specific terms for the person or the cancelled leave, but I wonder whether your colleague might have said "bump", not "pump".

I could understand someone referring to the leave being bumped, i.e. moved to a new position (date). (See definitions in The Free Dictionary).

The alternative day off may also be referred to (at least in the UK) as a "day off in lieu", i.e. as a day off instead of the public holiday. (See definition in Oxford Dictionary Online.) In fact, in the UK you will sometimes be entitled to two alternative days off if you were required to work on a public holiday.

You are looking for circumlocution.

Circumlocution (also called circumduction, circumvolution, periphrasis, or ambage) is locution that circles around a specific idea with multiple words rather than directly evoking it with fewer and apter words.

• For example, governmental income support to poor residents might be referred to as "welfare".

• Roundabout speech refers to using many words (such as "a tool used for cutting things such as paper and hair") to describe something for which a concise (and commonly known) expression exists ("scissors").

• The vast majority of definitions found in dictionaries are circumlocutory.

[Wikipedia]

OED definition of "circumlocution: "The use of many words where fewer would do, especially in a deliberate attempt to be vague or evasive".