Dorea is so not angry at these people anymore. 

"Out! OUT!"

Petunia and Dudley duck and use their arms to protect their faces as they try to dodge the letters and escape the kitchen.

Dorea leaves too. Someday she is going to tell him she got the very first letter and she's really looking forward to the look on his face when she does.

Uncle Vernon locks the kitchen door behind him.

"That does it," he says, trying to speak calmly but pulling great tufts out of his moustache at the same time. "I want you all back here in five minutes ready to leave. We're going away. Just pack some clothes. No arguments!"

--Okay that's actually kind of worrying.

Uncle Vernon hits Dudley round the head when he holds them up trying to pack his television, VCR, and computer in his sports bag, and in ten minutes they're in the car and driving.

While he sniffles quietly in the backseat.

...Uncle Vernon hit Dudley. Dorea thinks she's genuinely scared now.

They drive. And they drive. Even Aunt Petunia doesn't dare ask where they were going. Every now and then Uncle Vernon takes a sharp turn and drives in the opposite direction for a while. "Shake 'em off... shake 'em off," he mutters whenever he does this.

They don't stop to eat or drink all day. By nightfall Dudley's howling. He's never had such a bad day in his life. He's hungry, he missed five television programs he wanted to see, and he's never gone so long without blowing up an alien on his computer. Uncle Vernon stops at last outside a gloomy-looking hotel on the outskirts of a big city. Dudley and Dorea have to share a room with twin beds and damp, musty sheets.

Dorea doesn't sleep very well.

Dudley snores loudly.

That really doesn't help.

Uncle Vernon wakes them up at dawn and drags them to eat stale cornflakes and cold tinned tomatoes on toast for breakfast in the morning.

Where did Uncle Vernon even get stale cornflakes?

The terrible hotel they're staying at.

They've just finished when the owner of the hotel comes over to their table. "'Scuse me, but is one of you Ms. D. Potter? Only I got about an ’undred of these at the front desk." She holds up a letter so they can read the green ink address:

Ms. D. Potter
Room 17
Railview Hotel
Cokeworth

"That's me, but Uncle Vernon isn't going to let me have them."

"I'll take them," he says simply, and follows the woman to the front desk.

"Too much to hope this would make him give up," she mutters.

Yep.

Uncle Vernon pays and leads them to the car—no sign of the letters—and drives them for several hours still, into the middle of a forest, to the middle of a plowed field, halfway across a suspension bridge, and to the top of a multilevel parking garage. Finally, they reach the coast, where he parks, exits and locks them all inside the car, and disappears.

"Daddy's gone mad, hasn't he?" he asks Aunt Petunia.

...She's in agreement with Dudley about something, this is deeply weird.

"Perhaps," she says hesitantly. "I'll mention something when he comes back..."

It starts to rain, great drops beating on the roof of the car.

Dudley snivels. "It's Monday," he tells his mother. "The Great Humberto's on tonight. I want to stay somewhere with a television."

Odds of that would be...no.