I am not sure I have this right so here is what I understand.
You have a sitemap file with three sitemap files listed with about 120 pages each. And that these sitemap files are about a year old. I am going to work from that premise.
Given that, this is what I know. If you have only a few hundred pages, then just use one sitemap file. If your site changes, you should rewrite your sitemap to reflect updates to pages if at all possible including priorities, and update frequency. Google is not too concerned about smaller sitemaps where the site can be spidered. This may be why it has not read your sitemap files. It may not need to.
Content freshness and sitemap freshness are important. As well, the sitemap should add value to the spider such as pages that are not directly linked, queuing larger site pages, understanding content freshness, etc. Otherwise the sitemap will be all but ignored.
The best way to get Google to spider your site is to have fresh content. I assume that is the reason why you created the sitemap. If you do not need the sitemap, I would remove it. If you can add value like I mentioned above, then I would keep it. Either way, content freshness is the key to getting Google excited to spider your site. But you sitemap should be fresh too.
Best of Luck!