Actually, it's very easy to label work at this level complexity and proficiency. It doesn't matter if you are implementing Pastel for a 5-person company, rebuilding a network for an international conglomerate or updating a massive ERP system for the biggest banks in the world. When you update something, you test it first. You then create a rollback plan if it doesn't work well in the production environment. If it fails in the production environment, you roll back to the previous version of the stable system.
Exactly what constraints are holding them from following the same procedures as everybody else in IT? Might there be some system downtime involved? Well, it can't be worse than 4 straight days of complete system downtime for thousands of your customers, which is what you have right now. 0.3 MB might as well be 0 MB.
The fact that these clowns work in the US and EU make no difference. Every day incompetent software firms are sued for darn-near destroying businesses with their shoddy work. It happens in SA, it happens in the EU, it happens in the US. The fact that they worked through the night also means nothing. I can work through the night to try and build a spaceship. If the next day I haven't accomplished anything, nobody is going to give me a gold star for trying to do something and failing utterly at it.
I would actually encourage Afrihost to consider legal action against these vendors. They have lost you a lot of customers. They've certainly lost you my business.