Is there a way to update multiple pages without doing it one at a time?

I have built a site that is comprised of 20 similar but not identical landing pages that all use the X theme.

To give you an idea of what these pages look like, some of them include:
http://vmmed.com/service/en/xray/
http://vmmed.com/service/en/privatebreastcentre/
http://vmmed.com/service/en/ultrasoundbiopsy/ http://vmmed.com/service/en/arthrography/
http://vmmed.com/service/en/minorsurgeries/

If I want to make a cross-site change (such as to a phone number), I now have to go into 20 pages and update the text using the Visual Composer 20 times. Obviously this is time-consuming and inefficient. What are my options if I want to develop a more efficient approach? For instance, is there a way to develop a single text file into which I can place all of the text and update the text from that file?

Thanks.