they look great

Your concretor is never going to fix the problem he has created to your satisfaction and to an appropriate and professional standard of his own free will to remedy his laziness. I am assuming that he has been fully paid for his shoddy work. I wouldn't allow him (or his plumbing mate) anywhere near my property again. I would be paying my own plumber the $4500 to fix it, or get a few more quotes from some other plumbers - sometimes a clever plumber can work out a cost-effective workaround. Then speak to your lawyers to write some aggressive letters demanding compensation, but there is no guarantee that you will get what you are owed. Without knowing how big the slab is $2200 seems very cheap for the amount of work, bobcat hire and materials needed, and perhaps should have rung alarm bells about you get what you pay for. I would also be keeping the QBBC informed as this scam artist is giving registered tradesmen a bad name. Best of luck, and sorry for your bad experience Dr Retro of Dr Retro House Calls and Dr Retro Virtual Visits via Zoom.

I'm sorry you've had a bad experience. It's more common than it should be to be honest. Unfortunately, you're right in thinking the tiler didn't do the best job here. An unlevel concrete pad underneath can cause corners and edges of tiles to stick up higher than others, but that also could've been solved by using tile leveling clips that go under the tiles to level them up more evenly (extra cost). The tiles themselves could be slightly assymmetrical, but it still shouldn't create this kind of inconsistency in the spacing. It looks like the grout joints and spaces vary a lot. The tiler either didn't use spacers or he mixed up different spacer sizes. You could lighten the grout to match the tile colour so that it's not as obvious, but with lighter grout comes the issue of keeping it looking clean.

Thanks a lot for your reply, much appreciate it. The guy has been doing some work for me and he charges always reasonably so I don't ask for a quote from him. But for this work he said he will need a day and a half with his worker to finish the work and he said that the light frame I have for an internal fence would be good for the gate. Anyhow I was surprised when he constructed the current frame somewhere and brought it home and attached the wood to it. He didn't consult me regarding the new frame. I realized earlier that he is facing difficulties with the work but he dismissed my thoughts and assured me he will manage the work. I didn't discuss the width with him as the case with few jobs where I relied on his experience. Anyhow he got recently a contract for a big project and started delaying my work and I noticed some issues with another job I assigned him to do it because of lack of time. I had to return the motor I bought back to Bunnings after he said to me that he will google how to install it and when I saw that he is having trouble installing the rollers and the one he bought were not long enough. See attached image, he bought the one to the left when he should buy the one to the right. A friend of mine who is a builder examined the work and said there was no need to dig for a channel and it cold have been done without the channel by lifting the gate-guide and extending the length of the rollers or using larger rollers like the black one and he also said that the gate doesn't require such heavy frame.