HELP!! please!!! rat issues going on here!!! poison is not working!?

oooooooooooook ill start from the start.... we live in the UK and a few months ago i heard a noise coming from my kitchen cupboard... and the dog was sniffing and crying. so i empited it.. found a bag of dog food which had been chewed up so we put mouse traps down and poison and neither were touched. so i thought because there is a little hole at the back of the cupboard where the pipe goes out... a mouse had came in. and id scared it off. but the dog started sniffing around in the passage at the floor and crying and trying to dig up the floor. so my first thought was... its crawled under there and died and he can smell it. as the months went on i thought nothing of it... nothing else seamed to happen that would make me think HEYYY you have a rat infestation going on under your house. until a few weeks back i went in the garden to put some rubbish into my bin and there was a rat sitting there, i screamed and it dived into the bin. i shut the bin and ran into the house. i came out later that evening to investigate.... i found a piece of skirting board which was lying on the ground behind my bins and it was right against the house, the dog came out with me to investigate and thats where he lead me, i lifted it up to find a tunnel going under the house. i called up the council who sent a rat man out the next day, he put poison down... it was all taken, i put traps down, all in all i caught 8 rats, 7 babies and 1 bigger 1. he came back last week and put more poison down... it was taken within a few hours. i have not caught any rats since friday so i thought woooop they have gone!!! until this morning i went out and there was one in my garden.. it ran into my neighbors garden and into the vent in her wall which would lead under her living room. iv called up my landlord and they explained they probs have either moved into next door..... (which doesnt explain why the dog is still trying to dig up the passage even more than he was before) (unless he can smell dead ones) orrrrrrr they have found another way out of my house to avoid my traps. they said just wait for the rat man to come back on thursday, but thats two days away and i have 3 children, one a 8month old baby rolling around the floor, im very freaked out something might go wrong... one of my children may pick up a disease. im now thinking this problem may be bigger than i first thought.... what do i do? they are avoiding my traps and the poison doesnt seam to be killing them