TheUnexpected

I'm posting this message here in the hopes that someone can help me with my issue. I have a 2014 Skoda Octavia with (as far as i can tell) a Columbus MIB 5E0035020C The issues that first started were the sound that completely disappeared. Since that the device has been repaired by a firm here in the Netherlands, and the Sound is always on. But a new issue has occured since they updated the firmware. The phone function looks to be completely turned off. When i start the phone component it says 'telephone not available' (translated from Dutch). Also the bluetooth refuses to connect. I worry that the software update is the cause for this issue. Since this issue persists, the radio has been to the repair firm 3 times. They claim to fix this issue often, and that these types of radio rarely come back for repairs under 'warranty' . Is there for example any way to revert back to a previous version of the firmware? Perhaps overwrite the current firmware with the right one? Any help is greatly appreciated! Thanks!