I feel you pain OP, having endured a similar scenario with a low mileage 2012 K1600GT back in 2014. My mistake was to take a van delivery in January, with little chance to ride the thing seriously until Spring. So the faults didn't emerge as promptly as yours. However I was convinced I had been sold the previous owners problems, albeit unwittingly (possibly) but that's what a sound workshop check/PDI is all about..
All I can say is that everything got sorted, eventually & I was compensated modestly too - not that I view this as fair recompense for the down time & hassle. Your case is far stronger, as the deficiencies were spotted almost immediately. Here is the official complaints procedure, which you may have viewed already ........ https://www.bmw-motorrad.co.uk/en/service/ContactUs/customer-complaint-procedure.html . It works & I was content that BMW CS took the case seriously. However I never felt much respect from the supplying dealer as doubtless I stirred up a hornet's nest.
All I can say is that everything got sorted, eventually & I was compensated modestly too - not that I view this as fair recompense for the down time & hassle. Your case is far stronger, as the deficiencies were spotted almost immediately. Here is the official complaints procedure, which you may have viewed already ........ https://www.bmw-motorrad.co.uk/en/service/ContactUs/customer-complaint-procedure.html . It works & I was content that BMW CS took the case seriously. However I never felt much respect from the supplying dealer as doubtless I stirred up a hornet's nest.