Ouch! :-(
Just trying to work from your details, has it gone 17k miles since the last service (August 2020) with no oil change? How about oil top ups? I know MB did allow some flexibility on servicing due to the COVID situation a couple of years back but I don’t think that can be used as an excuse now.
I hate to say it, but if the engine hadn’t seized when would you have taken it in? Playing devils advocate, I know you’d said about the new year but it would have been pinging up for a service due since before last August (usually the ASSYST system calls for a service a month before, to give time to schedule it, so in July 2021?). It would have done this every day you drove it - and continued to do so every day since the service was due (exceeded). That’s quite a long time overdue and looks like you’ve covered quite a few miles also (exceeded the service interval both in terms of time and mileage).
Like I say, this is how MB will see it - and it’s unfortunate that the fault you have suffered could be intrinsically linked to the lack of servicing - ie possible lubrication failure or oil level etc.
Had it have been a faulty starter motor or water pump or something then I guess it maybe not such an awkward situation, but it doesn’t look good in these sorts of situations. No one on here can say that it would have still seized when it did if it had been serviced on time, you’ll never really know.
I’m sorry to hear of your woes and hope you can get some resolution, but in the context of balance I have to say I can understand both views and I’m not sure anyone can blame MB for their initial stance either, especially when the fault could be directly linked to the lack of servicing (oil condition, level and or condition of filter etc)
Hope you get something sorted out