Sevenoaks Town slipped to their heaviest Bostik League South defeat of the season on Saturday.
They started the first ever meeting between poorly conceding twice in the opening six minutes and it never got any better on a miserable afternoon matched by the weather.
Birthday boy Micky Collins included both new signings on the bench, Oliver Bennett and loan striker Sid Sollis on the bench.
However the game was already over as a contest when both were introduced.
Sittingbourne went into the game on the back of a seven-match losing streak, dropping them from second top to third bottom, while Oaks were bidding for a fourth successive away win.
Bourne went in front inside two minutes. Goalkeeper Patrick Lee’s Long free-kick was flicked on and Tom Loynes ran on to fire past Ben Bridle-Card.
The second came four minutes later Bourne defender Ben Fiitchett, heading home another free-kick.
Dover striker David Smith who spent a month on loan at Sevenoaks, before switching clubs was involved in two incidents.
First he collided with Bridle-Card as they challenged for the ball on the edge of the area, earning a yellow card, home connections thought harsh, then Tom Ripley was left nursing a bloody nose after another clash, which produced no reaction from referee Joe Stokes.
Oaks struggled to make any impact as an attacking force, apart from an early Kenny Pogue header that went just wide.
Things got worse four minutes before half-time, Smith making it 3-0 with his first goal in his second spell with Bourne.
The rain increased in the second half, skipper Frankie Sawyer struck the bar from 25 yards, and Ripley’s shot was saved by Lee.
Sollis, signed from Margate initially for a month, replaced Pogue, and showed some good touches, setting up Sawyer whose shot was blocked on the edge of the area.
Ripley pulled one back three minutes from time, getting on the end of a corner, before Gil Carvalho added Bourne’s fourth in stoppage-time.