Rat burrows

I've got a large rat burrow down the side of the house. The rats have moved in and I can hear them in the cavities in the back room around the fire. Pest control has been out and put a few boxes down. Last year they put some boxes down but the rats are smart it seems and didn’t eat much of the bait. They said there wasn’t much else they could do
I could fill in the burrow but surely they will just make a new one. I’m wondering if there is anything I can put down the burrow to scare them off. I’ve read cat urine is great, I don’t have a cat and they don’t seem scared of our dog. I could get hold of a litter tray and put that down. Or put the hose down the hole? Has anyone got any experience of getting rid of them? I’ve emptied the water butt to remove their water source, as suggested by Pest Control. We don't feed the birds but my neighbours do...
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Gardening in Central Norfolk on improved gritty moraine over chalk ... free-draining.
We’ve changed to this one, open the bags and pour it down the hole then cover with a slate or brick. Keep putting it down until you see some left.
https://www.amazon.co.uk/gp/product/B010E2GCIM/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1
If you can't afford to bring in a second company I'd consider doing as Lyn suggests. I've had good results with the bait she recommends - although I used it in the form of bait blocks.
Meanwhile ensure a wide area around the burrow is kept very clean and tidy with no plants or long grass to give the rats cover. Remove as many food sources as possible including fruit tree windfalls and open compost bins. Maybe your neighbours would agree to stop feeding the birds while you deal with the problem.
I liked the idea of putting fireworks down the burrow but the burrow leads to under the floorboards so I had better not.