Error text (text_description..) on shipping and payment page when checkout

Hi,
We are using Opencart since 2013.
When we upgraded the old website to Opencart 2.3.0.2 it works fine too!
Recently we started a new business and installed Opencart 2.3.0.2 and added products. Everything seems fine but here is a minor problem:
When customer check out, shipping and payment options title shows "text_title" (Free Delivery), "text_instruction" (Bank Transfer Instructions)...
If just one option for delivery and payment, customer can just click next button and confirm the order but we have more than 2 options for shipping and payment so should fix this problem asap. We hope someone here can help to fix this problem! Thanks in advance!
Screenshots attached herewith:

Hi

Verify that all required language files are included.
search in catalog\controller\checkout\*.* and check that this files exist in catalog/language/en-gb/xxxxxx/xxxxxx

Also look into php error log - there can be more information to allocate the problem