Owning your own home

Our bathroom has an electric towel rail mounted into a fully tiled wall.

its never worked properly since we moved in, the control unit was not working properly and only let you turn it on or off manually, now that unit is totally bust and we cant turn it on at all. Its ‘chrome’ but rusted badly. Googling it seems like an off brand very cheap unit.

We want to replace it with something better quality..

1. They dont seem to be very standard sizes so i guess we’re going to have to make new holes?
   
2. How easy is it to replace individual (square 10x10cm) tiles without ruining the wall?
   
3. I feel like i might need a professional.. who to call?