Is 2-3 Weeks really reasonable to repair an Appliance? I would be embarrassed if it took us 2-3 weeks to repair a computer in any but the most extreme circumstances. I would never leave the customer in a situation of being without one over the period either.
Write to Bosch you are rejecting the goods as not fit for purpose and give them 2 days notice to respond. If not, just go buy another one and lodge a DT case on them.