Faulty Navigator VI that BMW knows about.

I bought an extremely expensive Navigator VI, only to find out just after two years of probably only using it once a month, that it is a faulty unit and prone to problems. . . . . . . "I apologise for the unfortunately experience you have had with your BMW Navigator VI. *There were unfortunately lots of problems with these specific units.* BMW South Africa is currently offering a refund with a 20% depreciation per annum on the BMW Navigator VI. We would however need the GPS unit back with us, along with a copy of the invoice from purchase. We will then submit a claim to BMW South Africa and they will advise accordingly on the refund value." So they no longer replace the unit and offer 40% depreciation on a unit that they willingly sold, knowing that it has problems. Talk about a kick in the teeth. So provided I do get paid back the 60% of the "Depreciated Value" on a unit with no moving parts, I would still require an extra R6000+ to buy a replacement unit. Smells Rotten BMW.