HELP. Shower tray cracked

okay so I paid an English Builder to fit my new shower. I took out the bath and he fitted a reinforced shower base. He only laid the water pipes one mm under the tiles. Where these pipes are has caused cracking in the floor and the actual ceramic shower tray builder is taking no responsibility for it and is saying we must of had an earthquake bollocks we would of had cracks in the wall. Any way we have had to knock it all out.
My question is
1. How low should water pipes be
2. Is a ceramic base the strongest for a cave
3. Why no one tell me no to use English builders

A bit difficult to answer your earthquake question, as I can't see where you live, to be able to check.  

What sort of property do you live in?  If it is a house/cortijo, then the water pipes can run under the floorboards upstairs.  Not sure if you might have a solid floor downstairs?

If it is a cave/solid floor, it has been common practice for several years, that water pipes should run upwards from the appliance/shower/bath, up the wall and along to the outside.  No good builder will run pipework under a solid floor, unless there isn't an alternative.

Did your builder recommend you had the pipework re-done?

Laying pipes close to the surface is not a good idea.  Water pipes flex when very cold, or hot water run through them. This could then lead to the type of cracking you described. 

I would talk to your builder again.  Is he fully registered? 

If you want to double check, you can ask the Architect at the Town Hall to come and check the work.  They should also be able to recommend another builder, if you need one, but do check they are fully registered, before they start.  Many are not!

Caroline

It sounds like they didn't do a proper job! But that doesn't mean all English builders are bad at their job, anymore than anyone could say that all Spanish builders are brilliant!
It's a good idea to check they are registered as it should mean that they have the correct insurances.
I'm not sure what you mean by a ceramic base? We have two showers in our cave, both with pipes in the floor (but at a good depth - I helped dig out the trenches!), a concrete screed and tiled base. Never had any problems, touch wood.
Good luck wi getting it sorted out!