Have I hired a cowboy? plumbing advice

Have I hired a cowboy? We have a leak in a central heating pipe under the tiled floor in our downstairs bathroom. The water was seeping up through the floor. I called a plumber and he lifted the tiles and dug to reveal the pipe and find the leak. He has repaired the leak using compression joints (also repaired larger 28mm pipe which he punctured when digging), which he says are more reliable than soldering, but we have had constant leaks from each pipe every time the water is turned back on. Water is now off and boiler not working, so he is due back today. I have researched and found that compression joints should not be used under concrete and joints should be soldered. I also read pipes should be protected with Denso tape, but he says they need no protection. He is also going to fill the hole with rapid set tiling adhesive before refitting the tiles. Am I right to be worried?

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