In our old house, we got an infestation of mice and after catching about 30 in traps over 3 nights, I bought a 3 pack of the plug-in Sonic Rodent Repeller units that are supposed to drive them away.
After the first night of having them plugged in, no mice in the traps, same again after 2nd night. During the 3rd day, our neighbour told us of her sudden infestation - I got some of the Sonic Repellers for her and within 24hrs, her infestation had gone.
In the last 10 years, I've used these repellers in my garage and house and have not seen another mouse.
Same story with my mother in law's house - she had families of mice in her basement/cellar at the end of last year - "Pest Control" specialists spent 3 months taking her money, taking out dozens of mice in traps and putting down poison. But every morning, at least one trap had been triggered.
24hrs after putting 3 Sonic Repeller units in the basement/cellar on New Years Eve and a couple in the kitchen & living room (just in case they moved upstairs) - all of the traps were empty the next day and have been empty every day since.
I've been converted - I'd definitely give them a try (it's worth £15-£20 to find out IMO (B & Q have a few different types/brands).