[Noggo]

Does sound like a dodgy socket / plug connection. My sister had one go similar to what you are describing a couple a years ago. In her case I replaced both the socket and the plug and it's been fine since. As yours is a new dishwasher it will have a moulded plug and if you cut this off you may void the warranty.

All I can suggest is go for a good make like `MK' and not any of the B&Q, Focus or Homebase etc home brand options. I got the MK ones I used from Focus.