@Mlokole kwani you gave this guy a loan from the shylock business and he refused to pay.
On a serious note you seem to have let this chap intimidate you,you being his senior and all.
You need to intimidate the hell (no pun intended) out of him,when he sees you in the office he looks for the nearest exit or hides under the table.
'If you are not living on the edge,you are taking up too much space'
"We do not inherit the earth from our ancestors, we borrow it from our children" Native American Proverb