I have installed pebble tiles in several showersPros - very elegant, gives a sense of space as pebbles are different so no long defining linesCons - difficult to clean, must determine at outset if you want the stones deep in grout (you see lots more grout but the surface is smoother) or not so deep (you see less grout, but the surface is bumpier).Some people recommend epoxy grout, I don't for the simple reason it is much harder to get the grouting even with pebbles than tiles so more time needs to be taken.

That is a hard one with those tiles. I would have to think if you did a white, it would kind of work with the colour of your tiles. At the end of the day, they do need to be replaces, but as you said, due to budgeting reasons, you cannot, I can pass on this photo of a nice bathroom with those tiles for you though for inspiration... : )

Sounds like a very stressful situation! If there is absolutely no way the builder will allow you to change things (even if they did, I imagine they would ask you to foot the entire bill of pulling the tiles down and replacing all water proofing in addition to new tiles), I can make a few suggestions for improvement. Firstly I would suggest replacing the tiles above the vanity with a white mosaic, a patterned or a textured feature tile/strip. You could also use this same tile to replace the vertical feature in the shower. There are some beautiful shapes and sizes available to choose from. Secondly I would address the grout situation in this way: Floor - dark colour grout & Walls - Light colour grout. Lastly if it does not prove too difficult or expensive, maybe replace the tiles below the vanity with a plain white tile (could be similar size). Good luck and I am sure once you have a lovely mirror up and some crisp white towels, it will look just wonderful.

because the water could seep through the joints between the new tiles and sit between the two layers and affect the seal and also raise the height of the floor and affect the slope to the waste outlets..but, why do you want to retile if you're not using the bathroom??...for immediate resale consider bathroom wall to wall bathroom carpet, new wall paint, new vanity, taps and light fittings which should also be cheaper than tiling over the top and, if it's not allowed by the body corporate, it will be a risk to future sales as it should not satisfy a proper building inspection