I found the problem, I write it in public for the others.
ArXos sent me the complete Elxis Defender log and then it was clear that the problem derives from the Elxis CSS minifier.
The solution is to disable the minifier in Elxis configuration.

Hello Datahell.

The error comes when a visitor clicks on an image. Atter 3 clicks, he gets banned.
You can try it 

https://mousalim.gr/mousiko-skholeio/genikes-drasteriotetes/parelase-tes-28es-oktobriou.html

It seems that you have entered the image as blob (binary) data through the editor and Elxis Defender doesn't like it :-)
For the gallery, create a folder in media/images/, upload your images there, and then go to Gallery plugin and set it to load the images from that folder.

Hello Datahell

I am not sure that this solution works.
I made exactly as you said but still getting reports for PHP wrapper attack

Any other ideas ?
Regards

Also in case the sender name cannot be changed (like in Greece) then what the receiver sees as sender?

Test it to see by yourself. Usually a strange number.

I will tell you a story to understand why setting the sender is not allowed anymore. At the past you could add anything as a sender. You could set a text, like "Elxis" but also an other mobile number...

Consider this:
Your mobile phone: 111111
Your wife's mobile phone: 222222

I from Elxis send an SMS to your wife "222222" and set sender to "111111". I write as text "I want a divorce".
Your wife receives the message from you... and reads that you want a divorce...
Try to persuade her that you were not the one that sent the message. She will say "It was from your phone", buy YOU never send that message, I did. Got the problem?
PS. I have done the above trick a few times in my past as a joke to my friends (nothing serious, I am a good guy).

Same thing can happen with emails if there is no protection to prevent reaching their destination. Actually you can spoof many things in internet, some of them relatively easy.

In some cases you can use text as sender if you make a deal. Big companies do so. For instance when you receive an SMS from "Microsoft", from a bank, etc. You can contact your provider (instasent) and ask him.

Very good. Thank you for your time to reply in detail.

Elxis is not just a CMS, its an amazing framework, with it you can build anything. With IOT amazing things can be created.

I tried instasent because it was the most straight forward on pricing without too much things to read. It was the last on the list, but i think i will be fine 

I try to send sms in my phone in Cyprus and the sender is "Elxis". How can i change that? I know as you said sender cannot be changed for all countries but since most of the receivers will have Cyprus number then I want to change it.

Also in case the sender name cannot be changed (like in Greece) then what the receiver sees as sender?