Audi A6 AdBlue Tank/sensor fault

2019 40 TDI with 130000kms.

Got a warning and orange engine management light on dash.

Warning was “AdBlue/DEF fault: no restart in 1000km”.

Got this a few years back and main dealer replaced an adblue injector free of charge.

Got message again but it managed to clear itself after adblue topup and been fine for last 2 years roughly.

This time the OBD11 scan shows the following error which didn’t show on previous occasions:“U02A200 - Lost Communication with Reductant Quality Module”.

Main dealer have diagnosed it as a faulty sensor inside the tank which would require a full new tank at €2100k (€1900 of which is tank cost).

They checked the harness wires in/out of tank and no issue with that.

I’m thinking of getting some adblue additive cleaner that claims to prevent and breakdown crystal deposits in system, shot in the dark I know but maybe there is no communication as sensor has crystallised deposits on it. Something like Wynn's Ad Blue Crystal Clean.

Also considering if it would be worth getting a second option from a reputable Audi Indy if anyone has any recommendations? Would daltons in Portlaoise be a good place to get it checked out at?

I’m wary of deleting the adblue as will likely be looking to trade it in at the end of next year for something new or nearly new.