Drilling holes to mount shower unit

[Coaster]

Hi all,
Just to ask if when I'm fitting a shower or anything else to a tiled wall and the new holes to be drilled are very close to the old ones, how should I fill in the old holes?
the new holes being so close that I'd be partially drilling into the old holes.

 

[Diyisfun]

wont be easy, the drill is liable to slip into the old hole & also as side of the new hole will be against the old hole, it be a 'good fix', & is liable to fail.
You would be better off finding another position.