Hi,
The problem is UK grasses are not the same and do not grow here in Spain. Not unless you are a complete and dedicated fanatic with lots of money, time and water.
The solution is simple - use European, American or Spanish grasses not UK types - the climate is totally different.
But back to your problem.
There are many reasons why grass lawns do not do well in Spain - nearly all of them are easily solved.
The most tricky to spot are fungus deseases and underground pests like bugs etc.
I have found that most problems are down to the wrong type of grass.
I have spant many years (both in the UK and Spain) growing different types of grass, and after living here since 1982 I have come to the conclusion that there are really only three types of grass that people regard as "a lawn" that fit the bill of low maintenance, low watering and low mowing.
If you still want a beautiful lovely lawn email me on
lawnsinspain@yahoo.com.
Hope this helps
Greengrass