OK, got it.
Yeah, if they are buying low end radios and having problems, then it sounds typical. Someone looks up "walkie talkie" on Amazon and starts buying what ever looks cool and is cheap. It usually ends with what you are seeing, poor performance, etc.
I'd check into wether they actually have an FCC license or not. Probably not your job, but this could be an opportunity to lead them in the right direction and help them solve their communications issues.
Most of the big name manufacturers make "business" oriented radios that would fit your needs well. Icom and Kenwood have various models that are well built and will easily outperform the Chinese junk radios. On the Kenwood side, look at their ProTalk line. Those are basic radios that are "preprogrammed" in the sense that you would use a button sequence to set the radio to the frequency your company is licensed for and then lock it back down so they don't get changed.
They'll cost more than the Chinese radios, but they'll work better and will easily outlast them. More upfront cost, but they'll last a lot longer.
For your GMRS radio, you could get your GMRS license, or send the radio back.
If you are interested in getting your amateur radio license, there are much better options for suitable radios. The ham license doesn't provide any permissions on GMRS. It only gives permission on amateur radio frequencies. You'd need a suitable radio anyway. But, getting you ham license opens up a lot of options for you as an individual to learn the hobby and the technology. Many of us in the industry got our start that way.