Both of the elements in my boiler have failed, my own fault, I left it out in the rain for 2 weeks

So I've bit the bullet and bought a couple of 3kw jobbies off brew builder.
The problem is that the old, smoking, melted elements are 40mm holes, whereas the new ones are only 32mm.
Basically, I've got to plug two 40mm holes. Short of leaving the old elements in, any suggestions?
Cheers,
Jon.