I have 2 of them ultrasonic mouse reppelers and it has worked but for others they don't work so you may end up wasting your money
Reviews on them are sketchy. All I can say is they worked for me
Found this on the money saving expert forum and couldn't stop laughing
" Stop faffing around with traps, repellants and poisons.
Get a cat or borrow a neighbour's cat for an hour or two.
It'll be a bloodbath but it'll make an example of the first victim. :-D "