Welcome to Grows on you Rhonnie. You do not say where you are in Australia. It seems odd that a garden planner should have recommended a plant which is either not available or unsuitable for your growing conditions. I know that importing plants between states in Australia can be expensive and complicated but if you can say where you are maybe someone will be able to help you. I googled Lemon and Lime Hebe and there are suppliers in Oz but perhaps not close to you.

Well, oddly enough, seems to be impossible to find out the height and spread of Hebe Lemon and Lime - this one is not sold in the UK, so I'm having to restrict research to NZ or Aussie sites, and none give the measurement, other than saying compact, rounded, that kind of thing. Having looked at the plant, it has small fleshy leaves, and that usually indicates a good degree of resilience and hardiness, but its hard to recommend a substitute without being able to establish what size they get to. I'm also somewhat puzzled as to why it's called Lemon and Lime - pics just show plain green leaves with lighter, yellowish new leaves. Do you know yourself what the height and spread are?

I'd also be inclined to get in touch with whoever did the design for you and ask them what they think a good substitute would be, but otherwise, even not knowing the measurements of Lemon and Lime, I'd suggest considering Hebe ochracea James Stirling, or Hebe rakaiensis, or Hebe pinguifolia 'Pagei', or a mix of those. There's also Hebe Green Globe and Hebe odora (buxifolia).

Bamboo, Treetops, a nursery in Oz, says it is a 50cm x 50cm rounded bush with lemon stems and lime green leaves, if that is any help.

Most of the ones I mentioned are around that size, Scotsgran - the closest to Lemon and Lime is probably H. rakaiensis.

I don't know your climate - but in the uk I'd use something like Euonymous instead - good in light or shade and tough as old boots.
It is the problem with garden designers - they love to put plants in that look good on paper but don't necessarily do well in real life! I say this AS a garden designer myself !! - but I have had to replant many clients gardens - who have had expensive, award-winning garden designers - who really should know better..
If anyone is thinking of employing a garden designer - ask to see THEIR garden - and pictures of clients gardens - 3-5 years AFTER planting...! The real skill is in making a real garden - not one that just looks great for one season...

Boy, I agree with that Hoya105, but the design game is like every other game on the planet - some practitioners are very good, some are mediocre, others are awful. And Chelsea Show gardens don't help either - most people don't realise what they'll look like 2 months later if carried out in any ordinary garden. I am rather surprised that a shrub has been recommended which isn't suitable for the area - although I'm not sure I trust the nurseries to tell the truth either - it might be they just don't have that plant and use the 'not being suitable for the area' as an excuse.