Gradient not printing accurate from digital printing shop

What kinds of files are you sending to the printing company? Adobe Illustrator AI files or PDF files? I would ask the printing company about the kinds of printers they were using and the large format RIP software being used to run them. In order to print objects with freeform gradients it's critical for the RIP software to feature an Adobe certified PDF engine (not to mention be properly updated).

Another critical thing: if the printing company has to open your art file before printing, even if it is just for creating a PDF to import into the RIP software, they absolutely must open the file in Adobe Illustrator. Freeform gradients don't work outside an Adobe software environment. For instance, if they tried importing an AI file with freeform gradients into CorelDRAW, Affinity Designer or some other rival drawing application the gradient fills would break and/or be rasterized.

Was the artwork you gave the printer RGB or CMYK based? If you designed in RGB that could possibly explain some of the "muddy" print results. Purple colors can be really tricky to print, especially if they're RGB. It's easy to go outside a printer's gamut range capabilities when working in RGB. Some printers that have additional inks such as Light Magenta and Light Cyan can push things a good bit, but they're still limited on what they can print in RGB.

While it is true that everything gets rasterized before printing, it might still help to not send a live freeform gradient to the printer. Some prepress tech just cannot handle them well.

But on top of that, the printing process might also just lead to muddy results. But you might want to talk about the color issue with the printer separately. Because that could also happen no matter what you send them. Ask them what color spectrum is supported.