Rat problem

We have chooks and rats got in under their shed walls and were helping themselves at night despite my putting chilli powder and garlic grains in the feeder so now, when we shut them up for the night, we sweep up any dropped seeds and hook the feeder high up out of rat range. The two wompost bins that were alongside the hen house have been emptied and moved and sachets of rodent poison pushed down the holes but they seem now to be living under the grass paths and still tunnelling.

We've now created a flower bed where the compost bins were and I'll be planting it with alliums, chrysanthemums and lavender as rats don't like the smells but we have compost heaps all over our 1 hectare plot so it's a never ending battle and I don't mind them that much except for disturbing my chooks. We also have western whip snakes in the biggest compost heaps and they'll eat rodents but not come near the veg plot and hen house as we are there too often for their liking.