how long does it take for the motormounts and transmission to go bad.?

Typically, these components would not fail in three weeks. Engine and Transmission mount issues are common in this region. As far as the transmission failing, I would have to determine what caused the transmission to fail prior to giving you a proper course of action. Please let me know if there is anything else I can assist you with. Dan Prucha R&M Auto Repair Xperts (702)815-0444

Hello, did you buy this car from a private party or a dealership? If from a private party, you are probably entirely stuck. If from a dealership, I would seek some goodwill help from them. Did you have an independent inspection done prior to purchasing the vehicle? I am aware of some of these Mini vehicles where the automatic transmission can develop problems, but am not certain as to the cause of all the failures you are speaking of.