Contractors milking us for every dime? Question on this

Not a software developer – I work for a small company and for the past six months we’ve been paying four developers (2 on the app and 2 on our webpage) to add (what seem to me) to be very simple features.

Over the course of these six months, every single time anything is submitted it is riddled with bugs and must be fixed dozens of times and after six months of all this it still feels like we haven’t made much progress and things still aren’t really working smoothly for far too many users.

Now, some of these features do seem difficult – working with Siri to perform app functions, send texts through the app, etc.

But many of the issues/bug fixes are such simple stuff – like changing displays, numbers, words etc inside the app. And yet still it takes months even for those minor fixes.

How common is it for third party contractors to milk a company like mine for all were worth so we have to keep paying them for months and months on end to fix things and get the features just right?

Obviously I wish we’d just fire them and get new ones but I think our owners logic is that since they started it they kinda are the only ones who can finish it since only the understand the code? Idk, not too sure

Based off my limited info above, would you guys say were likely being taken advantage of, or that software dev is just expensive and takes time? Or is it too hard to tell with the limited info?

Sorry for the noob question and thank you for any feedback!