Hi Nicholas,
I'd avoid any automated programmes like this- did they explain how it works? Does it just pull the first line of your page text or product description or something similar to be your meta description? Lots of software can do this, but it's not necessarily the best way- your meta descriptions should be compelling for users who see them in search, and they don't directly impact your ranking anyway. Your meta titles can also be generated automatically, most CMS systems will do this for you automatically unless you override the description, or you'll be able to change your settings or add a module/plugin to do this (e.g. so that a product title is the meta title, followed by your brand name). What is your website built on? E.g. Wordpress, Magento, PrestaShop?
I wouldn't trust this company though, as you'll be able to make such improvements yourself, and worst case scenario they might hurt your rankings.
Hope this helps!
Zoe