COD issues. How to modify COD page, language and options?



I am facing some issues with COD payments (as everyone here).
I add an option of "standard (COD)" shipping method. So my customers can choose this first, and after at payment option the COD method.
The first issue is that some of my customers try to benefit or accidentally choose "standard" shipping method and after COD payment method (as Shopify don't have the option to handle COD fees etc.) so they don't get the extra charge from the COD payment.
The solution that i thought (as there is no other method to prevent this from Shopify) was to write a small text when the customer chooses the COD payment method, that announces that the "COD payment" has to be combined only with "Standard(COD)" shipping method to the previous page. Otherwise, the extra cost will be added from our store after the customer places the order.
The issue is that still, customers do the same thing, they choose the standard shipping method (and price of course) and COD payment. But is not so comfortable to announce them after the extra cost as they may feel offended or whatever and they may cancel the order.  
The second issue is that my store is based in Greece and i need to translate all pages. And neither Shopify's language edit page and neither my add on app (Translate My Store) doesn't recognize or locate the text under COD payment and also the text that appears after the customer places the order. So i wrote the message in Greek and some English together but is not so nice. I thought to make bold or red letters for the text to appear as a warning message so the customer can't claim that he didn't saw the text under the option. 
So my questions now.
1) Is there a solution to force the page to combine a shipping method with COD payment only? Like choosing only a particular shipping method like "Standard (COD)" and after to block other methods and make only the "COD" method available for payment.
Or the opposite. To let the customer choose COD payment only if he chooses the "Standard (COD)" shipping method? 
I guess that's the only solution to this issue. 

2)Is there a way to locate and modify the text under COD payment (except the option to edit the cod method on the settings page)? As i understand these fields are not located from any translation apps so the solution is to write straight in Greek and English the text from the settings page of the COD method. But i can't modify the text there to appear in Bolt or to do whatever i want. if someone knows a method would be helpful but as i understand i need to locate the code of the specific page and modify the HTML at least to appear in bolt or red (i know some basic things about modifying the code of the page).

Thanks in advance,

Triantafyllos Anastasiou

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Φιλε Τριανταφυλλε καλησπερα,

δεν εχω λυση απλα εχω το ιδιο προβλημα και νιωθω παρηγορια να το  μοιραζομαι μαζι σου.

Ειναι απαραδεκτο να υπαρχει ενα τοσο χοντρο ζητημα στο οποιο πολλοι ζητουν λυση πισω απο το 2016 και κανενας να μην ασχολειται.

Οποιος το βρει το σφυριζει και στον αλλον.

Μπηκα στο site σου. Εξυπνο αυτο που εκανες, αλλα... ΟΚ ειναι παντα προβλημα, οπως το γραφεις.




Hello Catsionson,

I reply in English as I think is more convenient for the community here.
Actually, a specialist gave me this solution as he mentioned that is the only way right now to add an extra amount to the COD shipping method and payment.
As I understand he said that the reason that they don't modify this it has to do with the regulations and laws. The specialist explained this to me and makes some sense. 
I know in Greece we are not used to that. But maybe according to the EU regulations, the stores that use the simple method to charge the COD fee with the way we know is not the right way.
So the solution that I suggest above to modify and "lock" the options is totally legal and maybe the only method that solves that issue right now.
Also after a talk with the support of Shopify, I realized that they don't give you the ability to modify even the language on the checkout page as they say that is a part of the code is only accessible from authorized programmers and not from everybody. 
I don't know if the specialists can reach and modify the code there but for sure if they can the price will be very high.
And in the end, I agree to the part that this issue, and a lot of other issues, should have been solved in days but still exists after years. 


Triantafyllos Anastasiou