If your current third-party product is barely functional and unsupported, it's clear that you need to consider a replacement as part of your mid-term strategy. It seems that there is a high risk of your vendor ceasing operations or their solution not being able to support your growth. The sooner you start the transition, the less painful it will be.
When deciding whether to build a replacement yourself, consider whether this solution could become a competitive advantage in the market. This is unlikely to be the case for a logistics company unless you plan to sell the software you build. From a business perspective, it's usually better to invest in your core strengths and outsource everything else as much as possible. Otherwise, securing the budget to hire the right talent in the right amounts will always be more challenging.
Assuming software is not your core strength, it may be wiser to search for one or several solutions that you can combine to support your strategy for decades while providing a certain level of flexibility. This might also mean building some parts of your system with low-code or even custom code, but I would try to keep that to a minimum.
If you still decide to build something custom, my recommendation would be to avoid replacing everything at once. Instead, replace your existing solution gradually. Start by rebuilding the most problematic functions first, and then add other features as you go. You might find along the way that some parts of the older solution's functionality are no longer needed.
As the founder of a low-code SaaS product (https://uibakery.io) and a service provider company (https://www.akveo.com), I can definitely relate to your challenges, which are quite similar to those of my clients. If you need any help with your transition, feel free to reach out at vlad a-t uibakery.io, and I can look at your use case in more detail or connect you with others who might help.
If it's actually unsupported, it could be a bargain.
Maybe OP should approach the company and offer to buy it, rights/source code etc, then build on top of that (it is doing what they want, even if barely...)
Very risky. It would only make sense if that solution does exactly what the OP needs but lacks stability and some new features. However, it's very likely that the product is a generic one, and the OP will end up spending the next couple of years supporting features they don't need but are interconnected with the ones they actually use. This would be especially challenging if they buy only the rights/code without the development team behind it.
When deciding whether to build a replacement yourself, consider whether this solution could become a competitive advantage in the market. This is unlikely to be the case for a logistics company unless you plan to sell the software you build. From a business perspective, it's usually better to invest in your core strengths and outsource everything else as much as possible. Otherwise, securing the budget to hire the right talent in the right amounts will always be more challenging.
Assuming software is not your core strength, it may be wiser to search for one or several solutions that you can combine to support your strategy for decades while providing a certain level of flexibility. This might also mean building some parts of your system with low-code or even custom code, but I would try to keep that to a minimum.
If you still decide to build something custom, my recommendation would be to avoid replacing everything at once. Instead, replace your existing solution gradually. Start by rebuilding the most problematic functions first, and then add other features as you go. You might find along the way that some parts of the older solution's functionality are no longer needed.
As the founder of a low-code SaaS product (https://uibakery.io) and a service provider company (https://www.akveo.com), I can definitely relate to your challenges, which are quite similar to those of my clients. If you need any help with your transition, feel free to reach out at vlad a-t uibakery.io, and I can look at your use case in more detail or connect you with others who might help.